Disc-shaped recording medium, disc driving device and disc producing method

ABSTRACT

With the disc-shaped recording medium, or the disc manufacturing method according to the present invention, for both the single-layer disc and the multi-layer disc, a recording layer L 0,  which is to be the first layer, is at the same distance, along the direction of disc thickness, from the surface of the cover layer CVLs on which falls the laser light. For the multi-layer disc, the second layer L 1  and the following layer(s) are formed at the locations which are closer to the cover layer CVLs than the first layer L 0.  Management information may be recorded by mobbling grooves, each layermay have tert areas, defect information, a replacement area. Thus, it is possible to improve compatibility, reliability and accessibility between a single-layer disc and a multi-layer disc. The spherical aberration for the recording/reproducing light may be controlled with respect to the selected layer.

TECHNICAL FIELD

This invention relates to a disc-shaped recording medium, such as anoptical disc, a disc producing method for producing the disc-shapedrecording medium, and a disc driving apparatus for the disc-shapedrecording medium.

This application claims priority of Japanese Patent Application No.2002-151185, filed on May 24, 2002, the entirety of which isincorporated by reference herein.

BACKGROUND ART

As a technique for recording and/or reproducing digital data, there is adata recording technique employing an optical disc, inclusive of amagneto-optical disc, such as, for example, CD (Compact Disc), MD(Mini-Disc), or DVD (Digital Versatile Disc), as a recording medium. Theoptical disc is a generic term for a recording medium comprised of adisc of a thin metal sheet protected with plastics and which isirradiated with laser light. A signal is read out as changes in thelight reflected from the disc.

The optical disc may be classified into a replay-only type, such as CD,CD-ROM or DVD-ROM, and a user-recordable type, such as MD, CD-R, CD-RW,DVD-R, DVD−RW, DVD+RW or DVD-RAM. Data recording on the user recordabletype disc is enabled by exploiting a magneto-optical recording system, aphase change recording system or a dye film change recording system. Thedye film change recording system, also termed a write-once recordingsystem, allows for data recording only once and does not allow forrewriting, and hence may be used with advantage for data storage. On theother hand, the magneto-optical recording system or the phase changerecording system allows for data rewriting and is utilized for a varietyof fields of application including recording of various content datasuch as music, pictures, games or application programs.

Recently, a high density optical disc, termed DVR (Data and VideoRecording) has been developed in an attempt to increase the data storagecapacity appreciably.

For recording data on a recordable disc, such as a disc of themagneto-optical recording system, dye film change recording system orthe phase change recording system, suitable guide means are necessitatedfor tracking to a data track. To this end, a groove is formed in advanceas a pre-groove, with the groove or a land (an area of a trapezoidalcross-section defined between neighboring grooves or neighboring turnsof the groove) being used as a data track.

It is also necessary to record the address information at a presetposition on the data track such as to permit data to be recorded at apreset location on the data track. There are occasions where thisaddress information is recorded by wobbling or meandering the groove.

Specifically, the sidewall section of the data recording track, formedin advance as a pre-groove, is wobbled in keeping with the addressinformation.

By so doing, the address may be read out from the wobbling information,obtained as the reflected light information during recording and/orreproduction, such that data can be recorded and/or reproduced at adesired location without the necessity of pre-forming bit data etc. onthe track for indicating the address.

By adding the address information as the wobbled groove, it isunnecessary to provide discrete address areas on the track to record theaddress as e.g., bit data, with the result that the recording capacityfor real data can be increased in an amount corresponding to the addressarea which might otherwise have to be provided as described above.

Meanwhile, the absolute time (address) information, expressed by thewobbled groove, is termed the ATIP (Absolute Time in Pre-groove) or ADIP(Address in Pre-groove).

It should be noted that if, in the high density disc, recentlydeveloped, such as DVR, recording and/or reproduction of phase changemarks is performed with a disc structure having a cover layer(substrate) of 0.1 mm along the direction of disc thickness, using acombination of the laser light with a wavelength of 405 nm, or so-calledblue laser light and an objective lens with a NA of 0.85, 23.3 GB(giga-byte) of data can be recorded on a disc of 12 cm in diameter, fora data block of 64 kB (kilobyte) as a recording and/or reproducing unit,with the track pitch of 0.32 μm and a line density of 0.12 μm, with theformat efficiency being approximately 82%.

If, with the similar format, the line density is set to 0.112 μm/bit,data with the capacity of 25 GB can be recorded and/or reproduced.

It is noted that there is raised a further drastically increased datacapacity, so that it may be contemplated that the recording layer is ofa multi-layer structure. For example, if the recording layer is of adouble layer structure, the recording capacity may be 46.6 or 50 GB, ortwice the above-mentioned capacity.

However, with the recording layer with a multi-layer structure, problemsare raised as to desirable disc layout or as to achieving operationalreliability.

There is also raised a problem as to achieving compatibility with thesingle layer optical disc.

It is also necessary to take into consideration the accessibility to thefirst and the following layers at the time of recording and/orreproduction.

DISCLOSURE OF THE INVENTION

In view of the above-depicted status of the art, it is an object of thepresent invention to provide a disc-shaped recording medium with pluralrecording layers, convenient in increasing the recording capacity or inimproving the recording and/or reproducing characteristics, a method forproducing the disc-shaped recording medium, and a disc drivingapparatus.

To this end, the disc-shaped recording medium according to the presentinvention is a multi-layer recording medium of a single-layer disc,having a single recording layer, and a multi-layer disc having aplurality of recording layers, wherein the recording layer as a firstrecording layer is formed at such a position in a direction of thicknessof the disc that the distance from the surface of a cover layer on whichthe light enters for recording and/or reproduction to the firstrecording layer is the same as the distance in case of the single layerdisc, and wherein the second recording layer is formed at such positionwhich is closer to the cover layer surface than the first layer.

The second recording layer is formed of a plurality of recording layers.

Of the first to the n-th recording layers, odd-numbered recording layersare recorded and/or reproduced from the inner rim towards the outer rimof the disc, and even-numbered recording layers are recorded and/orreproduced from the outer rim towards the inner rim of the disc.

The addresses of odd-numbered recording layers of the first to the n-threcording layers are sequentially recorded from the inner rim towardsthe outer rim of the disc, and the addresses of even-numbered recordinglayers are obtained on complementing the addresses of the odd-numberedrecording layers at the positions radially corresponding to theaddresses of the even-numbered recording layers, are recorded from theouter rim towards the inner rim of the disc.

A unique ID proper to the disc-shaped recording medium is recorded onlyin the first recording layer by a recording system of burning off therecording layer.

The management information for recording and/or reproduction is recordedas replay-only information in each of the first to the n-th recordinglayers by wobbling a groove formed for spirally extending in the disc.

A test area for conducting a recording test is provided in each of thefirst to n-th recording layers.

An area for recording the defect management information for each of thefirst to n-th recording layers is provided in each of the first to n-threcording layers.

A replacement area is provided in each of the first to n-th recordinglayers.

A disc driving apparatus according to the present invention may recordand/or reproduce data on a disc-shaped recording medium, which may be asingle-layer disc having a single recording layer, or a multi-layer dischaving a plurality of recording layers, wherein the recording layer as afirst recording layer of the multi-layer disc is formed at such aposition in a direction of thickness of the disc that the distance fromthe surface of a cover layer on which the light enters for recordingand/or reproduction to the first recording layer is the same as thedistance in case of the single layer disc, and wherein the secondrecording layer is formed at such position which is closer to the coverlayer surface than the first layer. The apparatus includes head meansfor illuminating the laser light for recording and/or reproducing datafor a track of each of the recording layers, correction means forcorrecting the spherical aberration of the laser light, and correctioncontrolling means for controlling the correction means, in dependenceupon the recording layer to be illuminated by the laser light to correctspherical aberration in dependence upon the recording layer.

The second recording layer is formed of a plurality of recording layers.

The correction controlling means causes the correction means to executespherical aberration correction for the first layer, on loading of thedisc-shaped recording medium, without regard to the disc type.

A unique ID proper to the disc-shaped recording medium, recorded in thefirst layer by a recording system of burning off the layer, is read outon loading the disc-shaped recording medium.

When the multi-layer disc having n recording layers, as the abovedisc-shaped recording medium, is loaded, the management information forrecording and/or reproduction, recorded as the replay-only informationby wobbling a spirally formed groove, is read out from one or more ofthe first to the n-th recording layers of the disc.

When the multi-layer disc having n recording layers, as the abovedisc-shaped recording medium, is loaded, test recording is carried outin a test area provided in each of the first to n-th recording layers.

For the multi-layer disc having n recording layers, the defectmanagement information for the first to the n-th recording layers isrecorded in a defect management area provided in each of the first ton-th recording layers.

When the multi-layer disc having n recording layers is loaded, recordingand/or reproduction is sequentially prosecuted from the first to then-th recording layers.

In recording and/or reproducing odd-numbered recording layers of thedisc-shaped recording medium, recording and/or reproduction is executedfrom the inner rim towards the outer rim of the disc and, in recordingand/or reproducing even-numbered recording layers of the disc-shapedrecording medium, recording and/or reproduction is executed from theouter rim towards the inner rim of the disc.

A method for producing, of a single-layer disc, having a singlerecording layer, and a multi-layer disc, having a plurality of recordinglayers, a disc-shaped recording medium which is the multi-layerrecording medium, includes forming the recording layer as a firstrecording layer at such a position in a direction of thickness of thedisc that the distance from the surface of a cover layer on which thelight enters for recording and/or reproduction to the first recordinglayer is the same as the distance in case of the single layer disc, andforming the second recording layer at such position which is closer tothe cover layer surface than the first layer.

The second recording layer is formed of a plurality of recording layers.

Of the first to the n-th recording layers, odd-numbered recording layersare recorded and/or reproduced from the inner rim towards the outer rimof the disc, and even-numbered recording layers are recorded and/orreproduced from the outer rim towards the inner rim of the disc.

The addresses of odd-numbered recording layers of the first to the n-threcording layers are sequentially recorded from the inner rim towardsthe outer rim of the disc, and the addresses of even-numbered recordinglayers are obtained on complementing the addresses of the odd-numberedrecording layers at the positions radially corresponding to theaddresses of the even-numbered recording layers, and are recorded fromthe outer rim towards the inner rim of the disc.

A unique ID proper to the disc-shaped recording medium is recorded onlyin the first recording layer by a recording system of burning off therecording layer.

The management information for recording and/or reproduction is recordedas replay-only information in each of the first to the n-th recordinglayers by wobbling a groove formed for spirally extending in the disc.

A test area for conducting a recording test is provided in each of thefirst to n-th recording layers.

An area for recording the defect management information for each of thefirst to n-th recording layers is provided in each of the first to then-th recording layers.

A replacement area is provided in each of the first to the n-threcording layers.

That is, the multi-layer disc, as a disc-shaped recording medium of thepresent invention, has the first layer position is common with thesingle layer disc, while the second layers ff., are closer to the coverlayer, thus assuring more advantageous characteristics.

Moreover, in the first to the n-th recording layers, the odd-numberedrecording layers are recorded and/or reproduced from the inner rimtowards the outer rim of the disc, while the even-numbered recordinglayers are recorded and/or reproduced from the outer rim towards theinner rim of the disc, thus advantageously achieving recording and/orreproducing tracing continuity for the respective layers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a groove of a disc according to the presentinvention.

FIG. 2 illustrates the groove wobbling of the disc according to thepresent invention.

FIG. 3 illustrates MSK modulated and HMW modulated wobble signalsaccording to the present invention.

FIGS. 4A to 4E illustrate MSK modulation according to the presentinvention.

FIG. 5 is a block diagram showing an MSK demodulating circuit fordemodulating the MSK modulated wobble signals according to the presentinvention.

FIG. 6 is a waveform diagram showing input wobble signals andsynchronous detected output signals.

FIG. 7 is a waveform diagram showing an integrated output value of thesynchronous output signal of the MSK stream, the held value of theintegrated output value and MSK demodulated data for modulation.

FIG. 8A to C illustrates HMW modulation according to the presentinvention.

FIG. 9 is a block diagram showing an HMW demodulation circuit fordemodulating the HMW modulated wobble signals.

FIG. 10 is a waveform diagram of the reference carrier signal, secondharmonics signals, data for modulation and the second harmonics signalsgenerated in dependence upon the data for modulation.

FIG. 11 is a waveform diagram of an HMW stream generated according tothe present invention.

FIG. 12A is a waveform diagram of a synchronous detected output signalof the HMW stream, according to the present invention, and FIG. 12B is awaveform diagram of an integrated output value of the synchronousdetected output signal, held values of the integrated output value andthe HMW demodulated data for modulation, according to the presentinvention.

FIG. 13 illustrates the disc layout according to the present invention.

FIGS. 14A and 14B illustrate wobbling of the RW and PB zones accordingto the present invention, respectively.

FIG. 15 illustrates a modulation system for the prerecorded informationaccording to the present invention.

FIGS. 16A and 16B illustrate an ECC structure of phase change marksaccording to the present invention.

FIGS. 17A to 17D illustrate an ECC structure of the prerecordedinformation according to the present invention.

FIG. 18A illustrates the frame structure of the phase change marksaccording to the present invention, and FIG. 18B illustrates the framestructure of the pre-recorded information according to the presentinvention.

FIG. 19A illustrates the relation between the RUB and the address unitof the disc according to the present invention, and FIG. 19B illustratesa bit block forming an address unit.

FIG. 20 illustrates a sync part of an address unit according to thepresent invention.

FIGS. 21A and 21B illustrate a monotone bit in a sync part and data forMSK modulation according to the present invention, respectively.

FIGS. 22A and 22B illustrate the signal waveform of a first sync bit inthe sync part and data for MSK modulation according to the presentinvention, respectively.

FIGS. 23A and 23B illustrate the signal waveform of a second sync bit inthe sync part and data for MSK modulation according to the presentinvention, respectively.

FIGS. 24A and 24B illustrate the signal waveform of a third sync bit inthe sync part and data for MSK modulation according to the presentinvention, respectively.

FIGS. 25A and 25B illustrate the signal waveform of a fourth sync bit inthe sync part and data for MSK modulation according to the presentinvention, respectively.

FIG. 26 illustrates a bit structure of a data part in an address unitaccording to the present invention.

FIGS. 27A, 27B and 27C illustrate the signal waveform of the ADIP bitrepresenting a bit “1” of the data part, data for MSK modulation, andthe HMW signal to be summed according to the present invention,respectively.

FIGS. 28A, 28B and 28C illustrate the signal waveform of the ADIP bitrepresenting a bit “0” of the data part, data for MSK modulation, andthe HMW signal to be summed according to the present invention,respectively.

FIG. 29 illustrates the address format according to the presentinvention.

FIG. 30 illustrates the content of the address information by the ADIPbit according to the present invention.

FIG. 31 is a block diagram showing an address demodulating circuitaccording to the present invention.

FIGS. 32A to 32E illustrate the control timing of an addressdemodulating circuit according to the present invention.

FIGS. 33A to 33C are wavelength diagrams showing the signal wavelengthobtained on HMW demodulation by the address demodulating circuitaccording to the present invention.

FIGS. 34A to 34C are wavelength diagrams showing the signal wavelengthobtained on HMW demodulation by the address demodulating circuitaccording to the present invention.

FIGS. 35A to 35C illustrate layered structures of a single-layer disc, adouble-layer disc and an n-layer disc according to the presentinvention, respectively, and FIG. 35D shows layer addresses accorded tothe respective recording layers of the respective discs.

FIG. 36 illustrates an areal structure of a single-layer disc accordingto the present invention.

FIG. 37 illustrates an areal structure of a double-layer disc accordingto the present invention.

FIG. 38 illustrates an areal structure of an n-layer disc according tothe present invention.

FIGS. 39A and 39B illustrate the spiral state of a disc according to thepresent invention.

FIG. 40 is a block diagram of a disc driving apparatus according to thepresent invention.

FIG. 41 is a flowchart for illustrating the processing of the discdriving apparatus according to the present invention.

FIG. 42 illustrates a mechanism for correcting the spherical aberrationof the disc driving apparatus according to the present invention.

FIGS. 43A and 43B illustrate a mechanism for correcting the sphericalaberration of the disc driving apparatus according to the presentinvention.

FIG. 44 is a block diagram of a mastering device according to thepresent invention.

FIG. 45 illustrates the procedure for manufacturing a disc according tothe present invention.

FIG. 46 is a block diagram of a BCA recording device according to thepresent invention.

BEST MODE FOR CARRYING OUT THE INVENTION

In the following, an optical disc embodying the present invention isexplained. In addition, a disc driving apparatus for recording and/orreproducing the optical disc (recording and/or reproducing apparatus)for recording and/or reproduction on or from the optical disc, amastering device for producing the optical disc and a BCA recordingapparatus, are explained. The explanation is made in the followingsequence:

1. Disc Wobbling System

1-1 Explanation of the Overall Wobbling System

1-2 MSK Modulation

1-3 HMW Modulation

1-4 Sum

2. Typical Application to DVR

2-1 Physical Properties of a DVR Disc

2-2 ECC Format of Data

2-3 Address Format

2-3-1 Relationship Between the Data for Recording and/or Reproductionand the Address

2-3-2 Sync Part

2-3-3 Data Part

2-3-4 Content of Address Data

2-4 Address Demodulation Circuit

3. Single Layer/Double Layer/n-Layer Disc

3-1 Layer Structure

3-2 Disc Layout

4. Disc Driving Apparatus

4-1 Structure

4-2 Disc Accommodating Processing

5. Disc Producing Method

5-1 Mastering Device

5-2 Producing Sequence

5-3 BCA Recording Device

1. Disc Wobbling System

1-1 Explanation of the Overall Wobbling System

An optical disc 1, embodying the present invention, includes a grooveGV, as a recording track, formed thereon, as shown in FIG. 1. Thisgroove GV is formed extending spirally from the inner rim towards theouter rim of the disc. Thus, the cross-section of the optical disc 1,taken along the radial direction, indicates convexed lands L and concavegrooves GV, formed in alternation with each other, as shown in FIG. 2.

It is noted that the spiral direction of FIG. 1 shows the state wherethe optical disc 1 is seen from its label side. It is also noted that,in the case of a disc having plural recording layers, the spiral statediffers from one layer to the next.

The groove GV of the optical disc 1 is formed meandering with respect tothe tangential direction, as shown in FIG. 2. The shape of themeandering of the groove GV is in keeping with the wobble signal. Thus,the optical disc drive is able to reproduce the wobble signal bydetecting both edges of the groove GV from the reflected light of alaser spot LS illuminated on the groove GV and by extracting thecomponents of variation of the edge positions relative to the radialdirection of the optical disc when the laser spot LS is moved along therecording track.

In the wobble signal, the address information of the recording track atthe recording position, that is the physical address and otheradditional information, has been modulated. Consequently, the opticaldisc drive is able to demodulate the address information etc from thewobble signal to control the address at the time of data recordingand/or reproduction.

Although the embodiments of the present invention are now explained forthe optical disc in which data is recorded in the grooves (grooverecording), the present invention may be applied to an optical disc inwhich data is recorded in the lands (land recording) or to an opticaldisc in which data is recorded in both the grooves and the lands(land/groove recording).

It is noted that the present embodiment of the optical disc 1 modulatesthe wobble signal with the address information in accordance with twomodulation systems. One of the modulation systems is the MSK (MinimumShift Keying) modulation system, while the other is such a system inwhich even-numbered harmonics are summed to the sinusoidal carriersignal and the polarity of the harmonics is changed with the sign of thedata for modulation to effect modulation. The modulation system whichsums even-numbered harmonics to the sinusoidal carrier signal andchanges the polarity of the harmonics with the sign of the data formodulation in order to effect modulation is termed HMW (Harmonic Wave)modulation.

With the present embodiment of the optical disc 1, such a wobble signalis generated in which a concatenation of a preset number of periods of asinusoidal reference carrier signal waveform of a preset frequency formsa block and in which the MSK modulated address information is insertedinto the block to form an MSK modulated section and the HMW modulatedaddress information is similarly inserted into the block to form an HMWmodulated section, as shown in FIG. 3. That is, the address informationbased on MSK modulation and the address information based on HMWmodulation are inserted at different locations in the block. Inaddition, one of the two sinusoidal carrier signals used in the MSKmodulation and the carrier signal for the MSK modulation represent theaforementioned reference carrier signal. The MSK modulated unit and theHMW modulated unit are located in different locations in the block andone or more periods of the reference carrier signal is arranged betweenthe MSK modulated unit and the HMW modulated unit.

In the following, that signal waveform portion in which no datamodulation has been made and only the frequency component of thereference carrier signal presents itself is referred to below as amonotone wobble. Moreover, in the following, the sinusoidal signal, usedas a reference carrier signal, is cos(ωt). One period of the referencecarrier signal is termed a wobbling period. The frequency of thereference carrier signal is constant from the inner rim to the outer rimof the optical disc and is determined in dependence upon the linearvelocity with which the laser spot is moved along the recording track.

1-2 MSK Modulation

The modulation methods used in the MSK modulation and in the HMWmodulation are hereinafter explained. First, the address informationmodulation system in accordance with the MSK modulation system isexplained.

The MSK modulation is the phase-continuous FSK (Frequency Shift Keying)modulation with the modulation index equal to 0.5. The FSK modulation isof such a system in which codes “0” and “1” of data for modulation areassociated with the two carrier signals with the frequencies f1 and f2.Stated differently, the FSK modulation is of a system in which, when thedata for modulation is “0” or “1”, a sinusoidal waveform with thefrequency f1 or a sinusoidal waveform with the frequency f2 is output,respectively. Moreover, in the phase-continuous FSK modulation, the twocarrier signals are phase-continuous at a sign switching timing of thedata for modulation.

In this FSK modulation the modulation index m is defined. Thismodulation index m is defined bym=|f1−f2|Twhere T is the rate of transmission of the data for modulation, that is1/(time of the shortest code length). The phase-continuous FSKmodulation with m=0.5 is termed the MSK modulation.

With the optical disc 1, the shortest code length of the data to be MSKmodulated is two wobbling periods, as shown in FIGS. 4A (a referencecarrier signal which is cos(ωt)) and 4B. Meanwhile, the shortest codelength L of the data for modulation may be optionally determinedprovided that the code length L is an integer number multiple of thewobbling periods which is not less than 2. It is noted that one of thetwo frequencies used for MSK modulation is the same as the frequency ofthe reference carrier signal, with the other being 1.5 times thefrequency of the reference carrier signal. That is, the one of the twosignal waveforms used in the MSK modulation is cos(ωt) or −cos(ωt), withthe other being cos(1.5ωt) or −cos(1.5ωt).

When data for modulation is inserted into the wobble signal of theoptical disc 1, a data stream of the data for modulation isdifferentially encoded in terms of a clock corresponding to the wobblingperiod as a unit, as shown in FIG. 4C. That is, the stream of the datafor modulation and delayed data obtained on delaying the referencecarrier signal by one period are processed with differential operation.Data obtained on this differential operation is termed pre-code data.

This pre-code data is then MSK-modulated to generate an MSK stream. Thesignal waveform of this MSK stream, shown in FIG. 4D, is such a one inwhich the signal waveform is the waveform of the same frequency as thatof the reference carrier (cos(ωt)) of the same frequency as thereference carrier or its inverted waveform (−cos(ωt)) when the pre-codedata is “0”, and in which signal waveform is the waveform of a frequency1.5 times the frequency of the reference carrier (cos(1.5ωt)) or itsinverted waveform (−cos(1.5ωt)) when the pre-code data is “1”. Thus, ifa data sequence of the data for modulation is of a pattern “010”, asshown in FIG. 4B, the MSK stream is of such a waveform comprised ofcos(ωt), cos(ωt), cos(1.5ωt), −cos(ωt), −cos(1.5ωt), cos(ωt), from onewobbling period to the next, as shown in FIG. 4E.

In the optical disc 1, the wobble signal is turned into theabove-described MSK stream to modulate the wobble signal with the datafor modulation.

It is noted that, when the data for modulation is differentially encodedand MSK modulated, as described above, synchronous detection of the datafor modulation becomes possible for the following reason:

With the differentially encoded data (pre-code data), the bit assertsitself (becomes “1”) at a code change point of the data for modulation.Since the code length of the data for modulation is set so as to be notless than twice the wobbling period, the reference carrier signal(cos(ωt)) or its inverted signal (−cos(ωt)) is necessarily inserted intothe latter half of the code length of the data for modulation. When thebit of the pre-code data is “1”, a sinusoidal waveform portion of afrequency 1.5 times the frequency of the reference carrier signal isinserted. At a code changeover point, waveform portions areinterconnected with phase matching. Consequently, the signal waveformportion, inserted in the latter half of the code length of the data formodulation, is necessarily the reference carrier signal (cos(ωt)) or itsinverted signal wavelength (−cos(ωt)) when the data for modulation is“0” or “1”, respectively. The synchronous detected output is positive ornegative if the output is in phase with or inverted with respect to thecarrier signal, respectively, so that modulated data may be demodulatedby synchronous detection of the MSK modulated signals with the referencecarrier signal.

Meanwhile, in MSK modulation, modulation takes place with phase matchingat a code changeover point, so that delay is produced before levelinversion of a synchronous detection signal. Thus, in demodulating theMSK modulated signal, an integration window of the synchronous detectionoutput is delayed by one-half wobbling period to realize a correctdetection output.

FIG. 5 shows an MSK demodulation circuit for demodulating the data formodulation from the above-described MSK stream.

Referring to FIG. 5, an MSK demodulation circuit 10 includes a PLLcircuit 11, a timing generator (TG) 12, a multiplier 13, an integrator14, a sample/hold (SH) circuit 15 and a slicing circuit 16.

A wobble signal (an MSK modulated stream) is input to the PLL circuit11. This PLL circuit 11 detects an edge component from the input wobblesignal to generate wobble clocks synchronized with the reference carriersignal (cos(ωt)). The so generated wobble clocks are sent to the timinggenerator 12.

The timing generator 12 generates the reference carrier signal (cos(ωt))synchronized with the input wobble signal. The timing generator 12generates a clear signal (CLR) and a hold signal (HOLD) from the wobbleclocks. The clear signal (CLR) is such a signal which is generated at atiming delayed by one-half period from the lead-in edge of the dataclock of the data for modulation having the two wobbling periods as theminimum code length. The hold signal (HOLD) is such a signal generatedat a timing delayed by one-half period from the trailing edge of thedata clock of the data for modulation. The reference carrier signal(cos(ωt)), generated by the timing generator 12, is supplied to themultiplier 13. The generated clear signal (CLR) is supplied to theintegrator 14. The generated hold signal (HOLD) is supplied to thesample/hold circuit 15.

The multiplier 13 multiplies the input wobble signal with the referencecarrier signal (cos(ωt)) to execute synchronous detection processing.The synchronous-detected output signal is supplied to the integrator 14.

The integrator 14 integrates the synchronous-detected signal from themultiplier 13. Meanwhile, the integrator 14 clears the integrated valueto zero at a timing of generation of the clear signal (CLR) by thetiming generator 12.

The sample/hold circuit 15 samples the integrated output value of theintegrator 14, at a timing of generation of the hold signal (HOLD) bythe timing generator 12, and holds the sampled value until occurrence ofthe next hold signal (HOLD).

The slicing circuit 16 binary-encodes the value held by the sample/holdcircuit 15, with the point of origin (0) as a threshold value, andoutputs the resulting bi-level signal as its sign is inverted.

An output signal of this slicing circuit 16 becomes the demodulated datafor modulation.

FIGS. 6 and 7 show the wobble signal (MSK stream) generated on MSKmodulating the data for modulation which is the data sequence “0010”,and output signal waveforms from respective circuit components when thewobble signal is input to the MSK demodulation circuit 10. In FIGS. 6and 7, the abscissa (n) denotes the period numbers of the wobblingperiod. FIG. 6 shows the input wobble signal (MSK stream) and asynchronous detection output signal of the wobble signal (MSK×cos(ωt)).FIG. 7 shows an integrated output value of the synchronous detectionoutput signal, the held value of the integrated output value, and thedata for modulation output demodulated from the slicing circuit 16.Meanwhile, the data for modulation output demodulated from the slicingcircuit 16 is delayed due to processing delay caused in the integrator14.

The synchronous detection of the data for modulation becomes possible incase the data for modulation is differentially encoded and MSK modulatedas described above.

In the optical disc 1, the MSK modulated address information is includedin the wobble signal, as described above. By MSK modulating the addressinformation and by including it in the wobble signal, high frequencycomponents included in the wobble signal are diminished to enableaccurate address detection. Moreover, since the MSK modulated addressinformation is inserted into the monotone wobble, the crosstalk whichmight otherwise be given to the neighboring track(s) may be diminishedto improve the S/N ratio. Additionally, with the present optical disc 1,in which the MSK modulated data can be demodulated on synchronousdetection, the wobble signal can be demodulated accurately and easily.

1-3 HMW Modulation

The address information modulating system, employing the HMW modulationsystem, is hereinafter explained.

The HMW modulation modulates digital codes by summing even-numberedharmonics signals to a sinusoidal carrier signal as described above andchanging the polarity of the harmonics signals in dependence upon thesign of the data for modulation.

With the optical disc 1, the carrier signal of the HMW modulation is thesignal of the same frequency and phase as those of the reference carriersignal (cos(ωt)) which is the carrier signal for the MSK modulation. Theeven harmonics signals to be summed to the carrier signal is the secondharmonics of the reference carrier signal (cos(ωt)), that is sin(2ωt) or−sin(2ωt), with the amplitude which is −12 dB with reference to theamplitude of the reference carrier signal. The minimum code length ofthe data for modulation is twice the wobbling period (period of thereference carrier signal).

When the code of the data for modulation is “1” or “0”, sin(2ω(t) or−sin(2ωt) is summed for modulation to the carrier signal, respectively.

FIG. 8 shows a signal waveform obtained on modulating the wobble signalin accordance with the above-described system. Specifically, FIG. 8(A)shows a signal waveform of the reference carrier signal (cos(ωt)). FIG.8(B) shows a signal waveform obtained on summing sin(2ωt) to thereference carrier signal (cos(ωt)), that is a signal waveform when thedata for modulation is “1”. FIG. 8(C) shows a signal waveform obtainedon summing −sin(2ωt) to the reference carrier signal (cos(ωt)), that isa signal waveform when the data for modulation is “0”.

Although the harmonics signals to be summed to the carrier signal arethe second harmonics in the above optical disc 1, any suitableeven-numbered harmonics, other than the second harmonics, may be summedas described above. Moreover, although only the second harmonics aresummed in the optical disc 1 as described above, plural even-numberedharmonics signals, such as the second and fourth harmonics, may also besummed simultaneously, as described above.

If positive and negative even-numbered harmonics signals are summed tothe reference carrier signal as described above, the data for modulationmay be demodulated by synchronous detection by the harmonics signals andby integrating the synchronous detection output for the code length timeduration of the data for modulation.

FIG. 9 shows an HMW demodulating circuit for demodulating the data formodulation from the HMW modulated wobble signal.

Referring to FIG. 9, an HMW demodulating circuit 20 includes a PLLcircuit 21, a timing generator (TG) 22, a multiplier 23, an integrator24, a sample/hold (SH) circuit 25 and a slicing circuit 26, as shown inFIG. 9.

The PLL circuit 21 is supplied with a wobble signal (HMW modulatedstream). The PLL circuit 21 detects an edge component from the inputwobble signal to generate wobble clocks synchronized with the referencecarrier signal (cos(ωt)). The so generated wobble clocks are sent to thetiming generator 22.

The timing generator 22 generates second harmonics signal (sin(2ωt))synchronized with the input wobble signal. The timing generator 22generates a clear signal (CLR) and a hold signal (HOLD) from the wobbleclocks. The clear signal (CLR) is generated at a timing of a lead-inedge of the data clock of the data for modulation in which the minimumcode length corresponds to two wobbling periods. The hold signal (HOLD)is a signal generated at the timing of a trailing edge of the data clockof the data for modulation. The second harmonics signal (sin(2ωt)),generated by the timing generator 22, is supplied to the multiplier 23.The generated clear signal (CLR) is supplied to the integrator 24, whilethe generated hold signal (HOLD) is supplied to the sample/hold circuit25.

The multiplier 23 multiplies the input wobble signal with the secondharmonics signal (sin(2ωt)) to carry out synchronous detectionprocessing. The synchronous detected output signal is supplied to theintegrator 24.

The integrator 24 integrates the synchronous detected signal from themultiplier 23. Meanwhile, the integrator 24 clears the integrated valueto zero at the timing of generation of the clear signal (CLR) by thetiming generator 22.

The sample/hold circuit 25 samples an integrated output value of theintegrator 24 at a timing of generation of the hold signal (HOLD) by thetiming generator 22 to hold the sampled value until such time the nexthold (HOLD) signal is produced.

The slicing circuit 26 binary-encodes a value held by the sample/holdcircuit 25, with the point of origin (0) as a threshold value, andoutputs the code for the value.

It is an output signal of the slicing circuit 26 that is to be thedemodulated data for modulation.

FIGS. 10 to 12 show a signal waveform used in HMW modulating the datafor modulation in the form of a data sequence “1010”, the wobble signalproduced on HMW modulation, and output signal waveforms from respectivecircuit components when the wobble signal is input to the MSKdemodulation circuit 20. In FIGS. 10 to 12, the abscissa (n) denotes theperiod numbers of the wobbling period. FIG. 10 shows the referencecarrier signal (cos(ωt)), data for modulation in the form of a datastring “1010” and a second harmonics signal waveform generated inassociation with the data for modulation (±sin(2ωt), −12 dB). FIG. 11shows the generated wobble signal (HMW stream). FIG. 12A shows asynchronous detection output signal of the wobble signal (HMW×sin(2ωt)).FIG. 12B shows an integrated output value of the synchronous detection,the held value of the integrated output value, and the data formodulation output demodulated from the slicing circuit 26. Meanwhile,the data for modulation output demodulated from the slicing circuit 26has been delayed due to order one delay caused in the integrator 14.

The data for modulation can be synchronous-detected, in case the datafor modulation is differentially encoded and HMW-modulated, as describedabove.

With the optical disc 1, the HMW modulated address data is included inthe wobble signal, as described above. By HMW modulating the addressinformation and including the resulting HMW modulated address data inthe wobble signal, it is possible to limit the frequency components andto reduce high frequency components. The result is that the demodulatedoutput of the wobble signal can be improved in S/N to provide foraccurate address detection. The modulation circuit can be formed by acarrier signal generating circuit, a circuit for generating its highfrequency components and a circuit for summing output signals of thesecircuits. Since the high frequency components of the wobble signal maybe reduced, cutting of an optical disc during its molding may befacilitated.

Since the HMW modulated address information is inserted into a monotonewobble, the crosstalk which might otherwise be given to the neighboringtrack(s) may be diminished to improve the S/N ratio. Additionally, withthe present optical disc 1, in which the HMW modulated data can bedemodulated on synchronous detection, the wobble signal can bedemodulated accurately and easily.

1-4 Sum

In the present embodiment of the optical disc 1, described above, theMSK demodulating system and the HMW modulating system are used as asystem for modulating the wobble signal with the address information. Inthe present optical disc 1, one of the frequencies used in the MSKdemodulating system is the sinusoidal signal (cos(ωt)) of same frequencyas that of the carrier frequency used in the HMW modulating system.Additionally, monotone wobbles, comprised only of the carrier signals(cos(ωt)), not modulated by data, are provided in the wobble signalbetween neighboring modulated signals.

With the present embodiment of the optical disc 1, the signals of thefrequencies used in the MSK modulation and the high frequency signalsused in the HMW modulation do not interfere with each other so that therespective signals are not affected by the modulation components of thecounterpart system during respective modulation processes. Consequently,the respective address information, recorded in the two modulationsystems, may be reliably detected to provide for improved accuracy incontrolling e.g., the track position at the time of recording and/orreproduction of the optical disc.

If the address information recorded with the MSK modulation and thatrecorded with the HMW modulation are of the same data content, theaddress information can be detected more reliably.

Moreover, with the present embodiment of the optical disc 1, in whichthe one of the frequencies used in the MSK demodulating system is thesinusoidal signal (cos(ωt)) of same frequency as that of the carrierfrequency used in the HMW modulating system, and in which the MSKdemodulation and the HMW modulation are performed at different sites inthe wobble signal, it is sufficient to sum the harmonics signals to theMSK modulated wobble signal at the wobble position for HMW modulation,at the time of modulation, thus enabling the two modulations to becarried out extremely simply. By executing the MSK demodulation and theHMW modulation at different locations in the wobble signal, and byproviding at least one monotone wobble between these differentlocations, it is possible to manufacture the disc more accurately and todemodulate the address more reliably.

2. Typical Application to DVR

2-1 Physical Properties of a DVR Disc

A typical application of the aforementioned address format to a highdensity optical disc, termed a DVR (Data and Video Recording), ishereinafter explained.

Typical physical parameters of the DVR disc, to which the presentaddress format is applied, are now explained. It should be noted thatthese physical parameters are merely illustrative such that the ensuingexplanation may be applied to an optical disc of other differentphysical characteristics.

An optical disc, which is to be the DVR disc of the present embodiment,is such an optical disc which carries out data recording in accordancewith the phase change system. As for the disc size, the diameter is 120mm and the disc thickness is 1.2 mm. That is, as for these points, thepresent optical disc is similar to a disc of the CD (Compact Disc)format or to a disc of the DVD (Digital Versatile Disc), insofar as theappearance of the disc is concerned.

The laser wavelength for recording and/or reproduction is 405 nm, suchthat the so-called blue laser light is used. The NA of the opticalsystem is 0.85.

The track pitch of tracks, on which phase change marks are recorded, is0.32 μm, with the line density being 0.12 μm. The format efficiency isapproximately 82%, with the 0 tablock at 64 kB as one recording and/orreproduction unit. The user data capacity of 23.3 GB is achieved with adisc with a diameter of 12 cm.

The data recording is of a groove recording system, as described above.

FIG. 13 shows the layout (area structure) of the overall disc.

As for the area on the disc, a lead-in zone, a data zone and a lead-outzone are provided, looking from the inner rim side.

As for the area pertinent to recording and/or reproduction, the innerrim area corresponding to the lead-in zone is a PB zone (playback orread-only area), while the area from the outer rim side of the lead-inzone to the lead-out zone is the RW zone (read/write or recording and/orreproduction area).

The lead-in zone is disposed more inwardly than the radius of 24 mm. Anarea between the radius of 21 mm and the radius of 22.2 mm is a BCA(Burst Cutting Area). In this BCA, there is recorded a unique ID properto the disc-shaped recording medium and which is obtained on burning offthe recording layer. Bar-code-like recording data are formed by formingconcentrically arrayed recording marks.

An area between the radius of 22.2 mm and the radius of 23.1 mmrepresents a pre-recorded zone (PR).

In the pre-recorded zone, there are prerecorded the disc information,such as recording and/or reproduction power conditions, and theinformation used for copy protection (pre-recorded information), bywobbling a spirally extending groove on the disc.

These represent non-rewritable replay-only information. That is, the BCAand the pre-recorded data zone represent the aforementioned PB zone(replay-only zone).

In the pre-recorded data zone, the copy protection information, forexample, is contained as the pre-recorded information. Using this copyprotection information, the following, for example, may be made:

In the present optical disc system, there is provided a medium key or adrive key, indicating that a registered drive device producer or aregistered disc producer is able to conduct business and has beenregistered for conducting the business.

In case of hacking, the associated drive key or medium key is recordedas the copy protection information. Based on this information, themedium or the drive having the medium key or the drive key may bedisabled for recording or reproduction. In the lead-in area, there areprovided a test write area OPC and a defect management area DMA in anarea between the radius of 23.1 mm and the radius of 24 mm.

The test write area OPC is used for test writing in setting therecording and/or reproduction conditions, such as laser power used inrecording and/or reproduction, phase change marks and so forth.

The defect management area DMA is an area in which the informationsupervising the defect information on the disc is recorded and/orreproduced.

The area between the radius of 24.0 mm and the radius of 58.0 mmrepresents a data zone. The data zone is an area used for recordingand/or reproducing user data based on phase change marks.

The area between the radius of 58.0 mm and the radius of 58.5 mmrepresents a lead-out zone. The lead-out zone may be provided with adefect management area, as in the lead-in zone, or may be used as abuffer area which may be overrun in seeking.

It is noted that the lead-out in the meaning of the terminal area forrecording and/or reproduction may be on an inner rim side in case of amulti-layered disc.

The disc area from the radius of 23.1 mm, that is from the test writearea, up to the lead-out zone, represents an RW zone (recording and/orreproducing area) in which the phase change marks are recorded and/orreproduced.

FIG. 14 shows the state of the tracks for the RW zone and the PB zone.Specifically, FIG. 14A shows groove wobbling in an RW zone, while FIG.14B shows the state of groove wobbling in a pre-recorded zone in the PBzone.

In the RW zone, the address information (ADIP) is previously formed bywobbling a groove formed extending spirally on a disc for tracking.

For the groove, carrying the address information, the information isrecorded and/or reproduced, based on the phase change marks.

Referring to FIG. 14A, the groove in the RW zone, that is the groovetrack, carrying the ADIP address information, has a track pitch TP=0.32μm.

On this track are recorded recording marks (RM) by the phase changemarks. The phase change marks are recorded to a line density of 0.12μm/bit or 0.08 μm/ch bit, in accordance with an RLL (1, 7) PP modulationsystem (RLL: Run Length Limited, PP: Parity preserve/Prohibit rmtr(repeated minimum transition run length)).

If a 1 ch bit is 1 T, the mark length is from 2 T to 8 T, with theshortest mark length being 2 T.

As for the address information, the wobbling period is 69T, with thewobbling amplitude WA being approximately 20 nm (p-p).

The address information and the phase change marks are designed so thatthe frequency ranges thereof will not overlap to eliminate possibleinfluence on detection.

The post-recording CNR (carrier noise ratio) value of the wobbling ofthe address information is 30 dB for a band width of 30 kHz, while theaddress error rate, inclusive of the perturbation (disc skew, defocusingor interference) is 1×10⁻³ or less.

It is noted that the track by the groove in the PB zone in FIG. 14B iswider in track pitch than the track by the groove in the RW zone in FIG.14A, with the wobbling amplitude being larger.

That is, the track pitch TP=0.35 μm, the wobbling period is 36 T and thewobbling amplitude WA is approximately 40 nm (p-p). The wobbling periodbeing 36 T indicates that the recording line density of the pre-recordedinformation is higher than the recording line density of the ADIPinformation. On the other hand, since the shortest duration of the phasechange marks is 2 T, the recording line density of the pre-recordedinformation is higher than that of the phase change marks.

In the track of this PB zone, no phase change marks are recorded.

While the wobbling waveform is recorded as a sinusoidal wave in the RWzone, it may be recorded as a sinusoidal wave or a rectangular wave inthe PB zone.

If the phase change marks are of a signal quality of the order of 50 dB,in terms of the CNR, for the bandwidth of 30 kHz, the symbol error rateafter error correction of 1×10⁻¹⁶ or less may be achieved in a knownmanner by appending the ECC (error correction code) to the data, so thatthe phase change marks may be used for data recording and/orreproduction.

The CNR of the wobble for the ADIP address information is 35 dB, in anon-recorded state of the phase change marks, for the band width of 30kHz.

As for the address information, this signal quality suffices, providedthat interpolation protection is made on the basis of the so-calledcontinuity check or discrimination. However, as for the pre-recordedinformation, recorded in the PB zone, the signal quality of 50 dB, interms of the CNR, or higher, equivalent to that of the phase changemarks, is desirable. For this reason, there is formed in the PB zone agroove physically different from the groove in the RW zone, as shown inFIG. 14B.

First, by enlarging the track pitch, the crosstalk from the neighboringtrack may be suppressed. By doubling the wobbling amplitude, the CNR canbe improved by +6 dB.

Moreover, by employing a rectangular wave as the wobbling waveform, theCNR may be improved by +2 dB.

Thus, the CNR may be 43 dB in total.

The recording bandwidth for the phase change marks and that for thewobble in the pre-recorded data zone are 18 T (one half of 36 T) and 2T, respectively, so that the CNR may be improved in this respect by 9.5dB.

Consequently, the CNR as the pre-recorded information is equivalent to52.5 dB. If the crosstalk from the neighboring track is estimated to be−2 dB, the CNR is on the order of 50.5 dB. This signal quality issubstantially equivalent to that of the phase change marks, and hencethe wobbling signals may safely be used for recording and/orreproduction of the pre-recorded information.

FIG. 15 shows the method for modulating the pre-recorded information forforming a wobbling groove in the pre-recorded data zone.

For modulation, FM codes are used.

FIGS. 15(a), 15(b), 15(c) and 15(d) show databits, channel clocks, FMcodes and the wobbling waveform, in vertical array.

One data bit is 2 ch (2 channel clocks). When the bit information is[1], the frequency of the FM code is one-half of the channel clockfrequency.

When the bit information is [0], the FM code is represented by thefrequency which is one-half of that of the bit information [1].

As for the wobble waveform, the FM code may directly be recorded by arectangular wave. Alternatively, it may also be recorded by a sinusoidalwave.

The FM code and the wobble waveform may be recorded as patterns shown inFIGS. 15(e) and 15(f), that is as patterns of opposite polarity to thatof FIGS. 15(c) and 15(d).

In the above-described FM code modulation pattern, the FM code waveformand the wobble waveform (sinusoidal waveform) when the data bit streamis [10110010] as shown in FIG. 15(g) are as shown in FIGS. 15(h) and15(i), respectively.

If the patterns shown in FIGS. 15(e) and 15(f) are used, the FM codewaveform and the wobble waveform (sinusoidal waveform) are as shown inFIGS. 15(j) and 15(k), respectively.

2-2 ECC Format of Data

Referring to FIGS. 16 to 18, the ECC format for the phase change marksand the pre-recorded information is explained.

First, FIG. 16 shows the ECC format for main data (user data) recordedand/or reproduced with the phase change marks.

There are two error correction codes (ECCs), namely the LDC (LongDistance Code) for main data 64 kB (=2048 bytes for one sector×32sectors) and BIS (Burst Indicator Subcode).

The main data of 64 kB, shown in FIG. 16A, are encoded as shown in FIG.16B. Specifically, 4 B of EDC (Error Detection Code) is appended to onesector of 2048 B and LDC is encoded for 32 sectors. The LDC is an RS(Reed-Solomon) code, with RS (248,216,33), code length of 248 and with adistance of 33. There are provided 304 code words.

As for the BIS, 720 B of data, shown in FIG. 16C, are ECC encoded, asshown in FIG. 16D. The BIS is the RS (Reed-Solomon code), with RS(62,30,33), codelength of 62, data of 30 and a distance of 33. There areprovided 24 codewords. FIG. 18A shows a frame structure for main data inthe RW zone.

The data of the aforementioned LDC and BIS make up a frame structure asshown. That is, data (38 B), BIS (1 B), data (38 B), BIS (1 B), data (38B), BIS (1 B) and data (38 B) are provided for one frame to make up astructure of 155 B. That is, each frame is formed by 38 B×4=152 B dataand BIS inserted at a rate of 1 B at an interval of 38 B.

A frame sync FS (frame synchronization signal) is arranged at thelead-in end of 1 frame of 155 B. There are 496 frames in one block.

As for the LDC data, even-numbered codewords of 0, 2, . . . are locatedat even-numbered frames of 0, 2, . . . , while odd-numbered codewords of1, 3, . . . are located at odd-numbered frames of 1, 3, . . . .

The BIS uses a code having a correcting capability higher than that ofthe LDC code, and corrects substantially all errors. That is, the BISuses a code with a distance of 33 for the codelength of 62.

Thus, the symbol of the BIS, in which an error has been detected, may beused as follows:

In ECC decoding, the BIS is decoded first. If, in the frame structure ofFIG. 18A, a BIS and the frame synchronization FS neighboring thereto areboth in error, data 38 B sandwiched therebetween are deemed to be inerror. To this data of 38 B, an error pointer is appended. In the LDC,this error pointer is used to make pointer erasure correction.

This leads to a correction capability superior to that in case of usingonly the LDC.

There is contained the address information in the BIS. This address isused in case there is no address information by the wobbled groove in aROM type disc.

FIG. 17 shows an ECC format for the pre-recorded information.

In this case, the ECC includes an LDC (Long Distance Code) for the maindata of 4 kB (two sectors each made up by 2048 B) and BIS (BurstIndicator Subcode).

The data of 4 kB, as the pre-recorded information, shown in FIG. 17A, isECC encoded, as shown in FIG. 17B. That is, 4 B of EDC (Error DetectionCode) is appended to 2048 B of main data and the LDC of two sectors areencoded. The LDC is an RS (Reed-Solomon) code with RS (248,216,33), acodelength of 248, 216 data and a distance of 33. There are provided 19codewords.

As for the BIS, 120 B of data shown in FIG. 17C is encoded, as shown inFIG. 17D. That is, BIS is an RS (Reed-Solomon) code with RS (62,30,33),a codelength of 62, 30 data and a distance of 33. There are providedfour codewords.

FIG. 18B shows a frame structure for the pre-recorded information in thePB zone.

The data of the LDC and the BIS make up a frame structure shown. Thatis, the frame sync FS (1 B), data (10 B), BIS (1 B), and data (9 B) arearranged for one frame to provide a structure of 21 B. That is, oneframe is made up by 19 B of data and 1 B of BIS.

The frame sync FS (frame synchronization signal) is arranged at thelead-in end of one frame. There are provided 248 frames in one block.

The BIS uses codes having a correcting capability higher than the LDCcode and corrects substantially all errors. Thus, the symbol of the BIS,in which an error has been detected, may be used as follows:

In ECC decoding, the BIS is decoded first. If a BIS and the framesynchronization FS neighboring thereto are both in error, data 10 B or 9B, sandwiched therebetween, is deemed to be in error. To this data of 10B or 9 B, an error pointer is appended. In the LDC, this error pointeris used to make pointer erasure correction.

This leads to a correction capability superior to that in case of usingonly the LDC.

There is contained the address information in the BIS. In thepre-recorded data zone, the pre-recorded information is recorded by thewobbled groove, so that there is no address information by the wobbledgroove, and hence the address in this BIS is used for accessing.

As may be seen from FIGS. 16 and 17, data by the phase change marks andthe pre-recorded information use the same code and the same structure,insofar as the ECC format is concerned.

This means that the processing of ECC decoding of the pre-recordedinformation can be carried out in the circuitry responsible for ECCdecoding in reproducing data by the phase change marks, so that thehardware structure as the disc driving apparatus may be improved inefficiency.

2-3 Address Format

2-3-1 Relationship Between the Data for Recording and/or Reproductionand the Address

A recording and/or reproducing unit in the present embodiment of the DVRdisc is a recording and/or reproducing cluster of a sum total of 498frames made up by an ECC block of 156 symbols×496 frames, and a linkarea of one frame for PLL appended to each side of the cluster, as shownin FIG. 18. This recording and/or reproducing cluster is termed a RUB(Recording Unit Block).

With the address format of the present embodiment of the optical disc 1,one RUB (498 frames) is supervised by three address units (ADIP_1,ADIP_2 and ADIP_3), recorded as wobble. That is, one RUB is recorded forthese three address units.

In this address format, one address unit is formed by a sync part of 8bits and a data part of 75 bits, totaling at 83 bits. In the presentaddress format, the reference carrier signal of the wobble signal,recorded in the pre-groove, is (cos(ωt)), and a bit of the wobble signalis formed by 56 periods of this reference carrier signal, as shown inFIG. 19B. Consequently, the length of one period of the referencecarrier signal (one wobble period) is 69 times one channel length ofphase change. The 56 periods of the reference carrier signal, formingone bit, are termed the bit block.

2-3-2 Sync Part

FIG. 20 shows a bit structure of a sync part in an address unit. Thesync part, used for discriminating the lead-in end of the address unit,is made up by first to fourth sync blocks (sync block “1”, sync block“2”, sync block “3” and sync block “4”). Each sync block is formed bytwo bit blocks, namely a monotone bit and a sync bit.

Referring to FIG. 21A, showing the signal waveform of a monotone bit,the first to third wobbles of the bit block, made up by 56 wobbles,represent a bit synchronization mark BM, with the fourth to 56thwobbles, next following the bit synchronization mark BM, being monotonewobbles (signal waveform of the reference carrier signal (cos(ωt)).

The bit synchronization mark BM is a signal waveform generated on MSKmodulation of data for modulation of a preset code pattern fordiscriminating the lead-in end of the bit block. That is, this bitsynchronization mark BM is a signal waveform obtained on differentiallyencoding the data for modulation of a preset code pattern and allocatingthe frequency in dependence upon the code of the differentially encodeddata. Meanwhile, the minimum codelength L of the data for modulationcorresponds to two wobble periods. In the present embodiment, a signalwaveform obtained on MSK modulating the data for modulation having onebit (two wobble periods) set to “1” is recorded as the bitsynchronization mark BM. That is, the bit synchronization mark BM is acontinuous signal waveform “cos(1.5ωt), −cos(ωt), −cos(1.5ωt)” in termsof a wobble period as a unit.

Consequently, the monotone bit may be generated by generating data formodulation “10000 . . . 00”, having a codelength of two wobble periods,and by MSK modulating the generated data for modulation, as shown inFIG. 21B.

It is noted that the bit synchronization mark BM is inserted not only asthe monotone bit in the sync part, but also at the lead-in end of eachof all bit blocks as now explained. Thus, during recording and/orreproduction, this bit synchronization mark BM may be detected tosynchronize the bit block in the wobble signal, that is the 56 wobblingperiods. Additionally, the bit synchronization mark BM may be used as areference for specifying the positions of insertion in the bit block ofeach of a variety of modulated signals as now explained.

In the signal waveform of the sync bit of the first sync block (sync “0”bit), made up by 56 wobbles, the first to third wobbles of the bit blockrepresent the bit synchronization mark BM, while the 17th to 19th and27th to 29th wobbles represent MSK modulation marks MM, with theremaining wobbles being all monotone wobbles in signal waveform, asshown in FIG. 22A.

In the signal waveform of the sync bit of the second sync block (sync“1” bit), made up by 56 wobbles, the first to third wobbles of the bitblock represent the bit synchronization mark BM, while the 19th to 21stand 29th to 31st wobbles represent MSK modulation marks MM, with theremaining wobbles being all monotone wobbles in signal waveform, asshown in FIG. 23A.

In the signal waveform of the sync bit of the third sync block (sync “2”bit), made up by 56 wobbles, the first to third wobbles of the bit blockrepresent the bit synchronization mark BM, while the 21st to 23rd and31st to 33rd wobbles represent MSK modulation marks MM, with theremaining wobbles being all monotone wobbles in signal waveform, asshown in FIG. 24A.

In the signal waveform of the sync bit of the fourth sync block (sync“3” bit), made up by 56 wobbles, the first to third wobbles of the bitblock represent the bit synchronization mark BM, while the 23rd to 25thand 33rd to 35th wobbles represent MSK modulation marks MM, with theremaining wobbles being all monotone wobbles in signal waveform, asshown in FIG. 25A.

Similarly to the bit synchronization mark BM, the MSK synchronizationmark is a signal waveform generated on MSK modulating the data formodulation of a preset code pattern. That is, the MSK synchronizationmark is a signal waveform obtained on differentially encoding the datafor modulation of a preset code pattern and allocating the frequency independence upon the sign of the differentially encoded data. Meanwhile,the minimum codelength L of the data for modulation corresponds to twowobble periods. In the present embodiment, a signal waveform obtained onMSK modulating the data for modulation having one bit (two wobbleperiods) set to “1” is recorded as the MSK synchronization mark. Thatis, the MSK synchronization mark is a continuous signal waveform“cos(1.5ωt) , −cos(ωt), −cos(1.5ωt)” in terms of a wobble period as aunit.

Thus, the sync bit (sync “0” bit) of the first sync block may begenerated by generating a data stream, having the codelength of twowobble periods, as shown in FIG. 22B, and by MSK modulating the sogenerated bitstream. In similar manner, the sync bit (sync “1” bit) ofthe second sync block, the sync bit (sync “2” bit) of the third syncblock and the sync bit (sync “3” bit) of the fourth sync block may begenerated by generating datastreams shown in FIGS. 23B, 24B and 25B andon MSK modulating the generated datastreams, respectively.

Meanwhile, a given sync bit has an insertion pattern to a bit block oftwo MSK modulation marks MM which is unique with respect to otherinsertion patterns of the MSK modulation marks MM to the bit block.Thus, by MSK demodulating the wobble signal, verifying the insertionpattern of the MSK modulation marks MM into the bit block and bydiscriminating at least one of the four sync blocks, during recordingand/or reproduction, the address unit can be synchronized to demodulateand decode a data part, which will now be explained in detail.

2-3-3 Data Part

FIG. 26 shows the structure of a data part in an address unit. The datapart is a portion of the address unit where real data of the addressinformation is stored. The data part is made up by 15, namely the firstto 15th ADIP blocks (ADIP block “1” to ADIP block “15”). Each ADIP blockis made up by one monotone bit and four ADIP bits.

The signal waveform of the monotone bit is similar to that shown in FIG.21.

The ADIP bit represents one bit of real data, with the signal waveformbeing changed with the code content.

If the code content represented by the ADIP bit is “1”, the first tothird wobbles, the13rd to 15th wobbles and the 19th to 55th wobbles ofthe bit block, composed of 56 wobbles, become the bit synchronizationmark BM, MSK modulation mark MM and a modulating part of the HMW “1”corresponding to sin(2ωt) summed to the reference carrier signal(cos(ωt)), with the waveform of the remaining wobbles being all monotonewobbles, as shown in FIG. 27A. That is, the ADIP bit, representing thecode content “1”, may be produced on generating data for modulation“100000100 . . . 00”, with the codelength corresponding to two wobbleperiods, as shown in FIG. 27B, MSK modulating the data for modulation,and on summing sin(2ωt) with an amplitude of −12 dB to the 19th to 55thwobbles of the MSK modulated signal waveform, as shown in FIG. 27C.

If the code content represented by the ADIP bit is “0”, the first tothird wobbles, the 15th to 17th wobbles and the 19th to 55th wobbles ofthe bit block, composed of 56 wobbles, become the bit synchronizationmark BM, MSK modulation mark MM and a modulating part of the HMW “0”corresponding to −sin(2ωt) summed to the reference carrier signal(cos(ωt)), with the waveform of the remaining wobbles being all monotonewobbles, as shown in FIG. 28A. That is, the ADIP bit, representing thecode content “0”, may be produced on generating data for modulation“1000000100 . . . 00”, with the codelength corresponding to two wobbleperiods, as shown in FIG. 28B, MSK modulating the data for modulation,and on summing −sin(2ωt) with an amplitude of −12 dB to the 19th to 55thwobbles of the MSK modulated signal waveform, as shown in FIG. 28C.

The ADIP bit has its bit content differentiated in dependence upon theposition of insertion of the MSK modulation mark MM, as described above.That is, the ADIP bit denotes a bit “1” or a bit “0”, in dependence uponwhether the MSK modulation mark MM is inserted in the 13th to 15thwobbles or in the 15th to 17th wobbles, respectively. Moreover, with theADIP bit, the same bit content as that denoted by the position ofinsertion of the MSK modulation mark MM is expressed by HMW modulation.Consequently, with the ADIP bit, the same bit content is denoted by thetwo different modulation systems, and hence the data can be decodedreliably.

FIG. 29 shows the format of the address unit, represented by combiningthe sync part and the data part, as described above.

In the address format of the present embodiment of the optical disc 1,the bit synchronization mark BM, MSK modulation mark MM and the HMWmodulation part are arranged discretely in one address unit, as shown inFIG. 29. Between respective modulated signal portions, there areinserted at least one wobble period of the monotone wobbles. The resultis that there is no interference between the respective modulatedsignals, thus achieving reliable demodulation of respective signals.

2-3-4 Content of Address Data

FIG. 30 shows an address format as the ADIP information recorded asdescribed above.

The ADIP address information has 36 bits, to which are appended 24parity bits.

The 36-bit ADIP address information is made up by 3 bits for multi-layerrecording (layer no. bit 0 to layer no. bit 2), 19 bits for RUB(Recording Unit Block) (RUB no. bit 0 to RUB no. bit 18) and 2 bits forthree address blocks for one RUB (address no. bit 0 and address no. bit1).

Additionally, 12 bits are provided as AUX data such as disc ID,recording the recording conditions, such as laser power for recordingand/or reproduction.

The ECC unit, as address data, is made up by a sum total of 60 bits andis formed by 15 nibbles, namely Nibble 0 to Nibble 14, where one nibbleis made up by four bits.

The error correction system is a nibble-based Reed-Solomon code (15, 9,7), with the four bits as one symbol. That is, the codelength is 15nibbles, the data is 9 nibbles and parity of 6 nibbles.

2-4 Address Demodulation Circuit

The address demodulating circuit for demodulating the addressinformation from the DVR disc of the above address format is hereinafterexplained.

FIG. 31 shows a block diagram of an address demodulating circuit.

The address demodulating circuit includes a PLL circuit 31, a timinggenerator for MSK 32, a multiplier for MSK 33, an integrator for MSK 34,a sample/hold circuit for MSK 35, a slicing circuit for MSK 36, a syncdecoder 37, an address decoder for MSK 38, a timing generator for HMW42, a multiplier for HMW 43, an integrator for HMW 44, a sample/holdcircuit for HMW 45, a slicing circuit for HMW 46, and an address decoderfor HMW 47, as shown in FIG. 31.

The PLL circuit 31 is supplied with wobble signals reproduced from theDVR disc. The PLL circuit 31 detects an edge component from the inputwobble signal to generate wobble clocks synchronized with the referencecarrier signal (cos(ωt)). The generated wobble clocks are supplied tothe timing generator for MSK 32 and to the timing generator for HMW 42.

The timing generator for MSK 32 generates the reference carrier signal(cos(ωt)) synchronized with the input wobble signal. The timinggenerator for MSK 32 also generates the clear signal (CLR) and the holdsignal (HOLD) from the wobble clocks. The clear signal (CLR) isgenerated at a timing delayed by one half wobble period from the lead-inedge of the data clock of the data for modulation having two wobbleperiods as the minimum codelength. The hold signal (HOLD) is generatedat a timing delayed by one half wobble period from the trailing edge ofthe data clock of the data for modulation. The reference carrier signal(cos(ωt)), generated by the timing generator for MSK 32, is supplied tothe multiplier for MSK 33. The generated clear signal (CLR) is suppliedto the integrator for MSK 34. The generated hold signal (HOLD) issupplied to the sample/hold circuit for MSK 35.

The multiplier for MSK 33 multiplies the input wobble signal with thereference carrier signal (cos(ωt)) to perform synchronous detectionprocessing. The synchronous detected output signal is sent to theintegrator for MSK 34.

The integrator for MSK 34 integrates the signal synchronous-detected bythe multiplier for MSK 33. This integrator for MSK 34 clears theintegrated value to zero at the timing of generation of the clear signal(CLR) by the timing generator for MSK 32.

The sample/hold circuit for MSK 35 samples the integrated output valueof the integrator for MSK 34, at the timing of generation of the holdsignal (HOLD) by the timing generator for MSK 32, and holds the sampledvalue until the next hold signal (HOLD) is produced.

The slicing circuit for MSK 36 binary-encodes the value held by thesample/hold circuit for MSK 35, with the point of origin (0) as athreshold value, and inverts the sign of the binary signal to output theresulting signal.

The output signal from this slicing circuit for MSK 36 becomes the MSKdemodulated datastream.

The sync decoder 37 detects the sync bit in the sync part from the bitpattern of the demodulated data output from the slicing circuit for MSK36. The sync decoder 37 synchronizes the address unit from the detectedbit. Based on the synchronization timing of the address unit, the syncdecoder 37 generates an MSK detection window, indicating the wobbleposition of MSK modulated data in the ADIP bit of the data part, and anHMW detection window, indicating the wobble position of HMW modulateddata in the ADIP bit of the data part. FIGS. 32A, 32B and 32C show thesynchronization position timing of the address unit detected from thesync bit, the timing of the MSK detection window and the timing of theHMW detection window, respectively.

The sync decoder 37 supplies the MSK detection window and the HMWdetection window to the address decoder for MSK 38 and to the timinggenerator for HMW 42, respectively.

The address decoder for MSK 38 is supplied with a demodulated stream,output from the slicing circuit for MSK 36, and detects the position ofinsertion of the MSK modulation mark MM in the ADIP bit of thedemodulated datastream, based on the MSK detection window, to verify thecontent of the code represented by the ADIP bit. If the insertionpattern of the MSK modulation mark MM in the ADIP bit is of a patternshown in FIG. 27, the address decoder for MSK 38 verifies the codecontent to be “1”, whereas, if the insertion pattern of the MSKmodulation mark MM in the ADIP bit is of a pattern shown in FIG. 28, theaddress decoder for MSK 38 verifies the code content to be “0”. The theaddress decoder for MSK outputs a bit sequence obtained from theverified result as the MSK address information.

From the wobble clocks, the timing generator for HMW 42 generates secondharmonics signal (sin(2ωt)) synchronized with the input wobble signal.From the HMW detection window, the timing generator for HMW 42 generatesthe clear signal (CLR) and the hold signal (HOLD). The clear signal(CLR) is generated at the timing of the lead-in edge of the HMWdetection window. The hold signal (HOLD) is generated at the timing ofthe trailing edge of the HMW detection window. The second harmonicssignal (sin(2ωt)), generated by the timing generator for HMW 42, issupplied to the multiplier for HMW 43. The generated clear signal (CLR)is supplied to the multiplier for HMW 43, while the generated holdsignal (HOLD) is supplied to the sample/hold circuit for HMW 45.

The multiplier for HMW 43 multiplies the input wobble signal with thesecond harmonics signal (sin(2ωt)) for executing synchronous detectionprocessing. The synchronous detected output signal is supplied to theintegrator for HMW 44.

The integrator for HMW 44 integrates the signal synchronous detected bythe multiplier for HMW 43. Meanwhile, this integrator for HMW 44 clearsthe integrated value to zero at the timing of generation of the clearsignal (CLR) by the timing generator for HMW 42.

The sample/hold circuit for HMW 45 samples the integrated output valueof the integrator for HMW 44, at the timing of generation of the holdsignal (HOLD) by the timing generator for HMW 42, and holds the sampledvalue until generation of the next hold signal (HOLD). That is, thereare 37 wobbles of the HMW modulated data in one bit block, so that, ifthe clear signal (HOLD) is generated at n=0, where n denotes the numberof wobbles, as shown in FIG. 32D, the sample/hold circuit for HMW 45samples the integrated value at n=36, as shown in FIG. 32E.

The slicing circuit for HMW 46 binary-encodes the value held by thesample/hold circuit for HMW 45, with the point of origin (0) as athreshold, and outputs the code for the value.

The output signal from this slicing circuit for HMW 46 becomes ademodulated datastream.

From the demodulated datastream, the address decoder for HMW 47 verifiesthe content of the code, represented by the respective ADIP bits, andoutputs the bit sequence, obtained from the verified result, as the HMWaddress information.

FIG. 33 denotes each signal waveform when the ADIP bit with the codecontent “1” is HMW modulated by the address demodulating circuit 30. InFIG. 33, the abscissa (n) denotes the period numbers of the wobblingperiod. FIG. 33A shows the reference carrier signal (cos(ωt)), data formodulation with the code content of “1” and the second harmonics signalwaveform (sin(2ωt), −12 dB) generated responsive to the data formodulation. FIG. 33B shows the generated wobble signal. FIG. 33C showsthe synchronous detected output signal for this wobble signal(HMW×sin(2ωt)), an integrated output value of the synchronous detectionoutput signal, a held value of the integrated output and the data formodulation output demodulated from the slicing circuit 46.

FIG. 34 shows each signal waveform on HMW demodulation by the addressdemodulating circuit 30 of the ADIP bit with the code content of “0”. InFIG. 34, the abscissa (n) denotes the period numbers of the wobblingperiod. FIG. 34A shows the reference carrier signal (cos(ωt)), data formodulation with the code content of “1” and the second harmonics signalwaveform (−sin(2ωt), −12 dB) generated responsive to the data formodulation. FIG. 34B shows the generated wobble signal. FIG. 34C shows asynchronous detection output signal (HMW×sin(2ωt)) of this wobblesignal, an integrated output value of the synchronous detection outputsignal, a held value of this integrated output and the data formodulation output demodulated from the slicing circuit 46.

In this manner, the address demodulating circuit 30 is able to detectthe synchronous information of the address unit, recorded with MSKmodulation, and to execute MSK demodulation and HMW demodulation, basedon the detection timing.

3. Single Layer/Double Layer/n-Layer Disc

3-1 Layer Structure

The DVR optical disc 1 of the above-described embodiment may beclassified into a single-layer disc, with a single recording layer, anddouble- or three-layer discs, these being collectively termed amulti-layer disc or an n-layer disc, where n denotes the number oflayers.

Of course, the recording capacity can be drastically increased byproviding a large number of recording layers. In the present embodiment,such a multi-layer disc which, as a preferred structure of suchmulti-layer disc, may assure compatibility, accessibility andreliability of the respective disc sorts associated with the respectivenumbers of the layers, is to be achieved.

FIGS. 35A to 35C schematically show the layered structure of thesingle-layer, double-layer and n-layer discs. FIG. 35D shows layeraddresses accorded to the respective recording layers of the respectivediscs.

The disc thickness is 1.2 mm, with the thickness of the substrate RL ofpolycarbonate being approximately 1.1 mm.

A light beam from a disc driving apparatus for recording and/orreproducing data on the optical disc 1 is shown with a chain-dottedline. The light beam is the blue laser light with the waveform of 405nm, and is collected from a CVL side of the cover layer (substrate), asshown, by an objective lens with a NA of 0.85.

In the case of the single layer disc of FIG. 35A, a recording layer L0of the phase change recording layer is formed on a substrate RL with athickness of for example 1.1 mm, and the cover CVL 100 μm in thicknessis formed thereon.

During recording and/or reproduction, the light beam is condensed on arecording layer L0 from the side of the cover layer CVL.

The layer address of the recording layer L0 is [0].

In the case of the double-layer disc of FIG. 35B, the recording layer L0as a phase change recording layer is formed on a substrate RL 1.1 mmthick and a recording layer L1 as a second phase change recording layeris formed thereon, with an intermediate layer ML of 25 μm in-between.The cover layer CVL 75 μm in thickness is formed thereon.

During recording and/or reproduction, the light beam is condensed fromthe side of the cover layer CVL to the recording layers L0 ad L1.

The layer address of the first recording layer L0 is [0], while thelayer address of the second recording layer L1 is [1]. Recording and/orreproduction is carried out in the order of the layer address [0] andthe layer address [1].

As in the case of the single-layer disc, the first recording layer L0 isformed at a position of 100 μm from the surface CVLs of the cover layerCVL.

In the case of the n-layer disc of FIG. 35C, the recording layer L0 ofthe phase change recording film is formed on the substrate RL 1.1 mm inthickness, and the recording layer L1 of the second phase changerecording film is formed thereon, with interposition of an intermediatelayer ML 25 μm in thickness. The third recording layer ff., are alsoformed as recording layers of the phase change recording film, withinterposition of respective intermediate layers ML. That is, the n-thlayer is formed as a recording layer of the phase change recording film,with interposition of the intermediate layer ML.

The thickness of the cover layer CVL is 100−(n-1)×25 μm.

During recording and/or reproduction, the light beam is condensed on therecording layers L0, L1, . . . , Ln from the side of the cover layerCVL.

The layer address of the first recording layer is [0], that of thesecond recording layer L1 is [1] and so forth, with the layer address ofthe n-th recording layer being [n-1]. Recording and/or reproduction forthe respective recording layers is in the sequence of the layeraddresses [0], [1], . . . [n-1].

As in the case of the single layer and double layer discs, the firstrecording layer L0 is formed at a position of 100 μm from the surfaceCVLs of the cover layer CVL.

Thus, in the single-layer, double-layer and in the n-layer disc, therecording layer L0 of the first phase change recording film is formed ata distance of 100 μm from the surface CVLs of the cover layer CVL. Inthe multi-layer disc, the recording layers L1, L2, . . . , L(n-1) of thesecond to n-th phase change recording films are arranged closer towardsthe cover layer surface CVLs than the first recording layer L0.

Consequently, in the single-layer, double-layer and in the n-layer disc,the first recording layer L0 may be formed in similar fashion on apolycarbonate substrate RL so that the manufacturing process for thesingle-layer may partly be used in common with that for the double-layerand the n-layer disc, while the first recording layers L0 of thesingle-layer, double-layer and in the n-layer disc may be of similarrecording and/or reproducing characteristics.

Moreover, in the multi-layered disc, the second recording layers ff.,that is the recording layers (L1, . . . L(n-1)) may be arranged closertowards the cover layer surface CVLs, so that the distance from thesecond to n-th recording layers to the cover layer surface becomesprogressively shorter, that is the cover layer thickness becomesprogressively thinner in this sequence. This increases the tilt angleallowance between the disc and the light beam.

Consequently, the recording and/or reproducing characteristics of thesecond to n-th recording layers can be relaxed as compared to those ofthe first recording layer L0, thus improving the productivity andreducing the cost of the disc 1 as the multi-layered disc.

In recording and/or reproducing the first to the n-th recording layersof the multi-layered disc, a light beam is condensed on the respectiverecording layers and, because of the different distances from the coverlayer surface CVLs to the respective recording layers, the sphericalaberration is corrected from one recording layer to the next.

In the single-layer, double-layer and in the n-layer disc, the firstrecording layer L0 is unexceptionally formed at a distance of 100 μmfrom the cover layer surface CVLs. Thus, by correcting the sphericalaberration to the first recording layer L0 in the optical head, beforeor during loading the disc on the disc driving apparatus, the light beammay be optimally converged on the first recording layer L0 having thelayer address [0], without dependency on which of the single-layer disc,double-layer disc and the n-layer disc has been loaded, so that therecording and/or reproduction may be commenced at the layer address [0].

These operations will be explained subsequently in detail in connectionwith the processing by the disc driving apparatus.

Although the recording films of the respective recording layers,described above, are phase change films, the above-described layerstructure and the meritorious effect derived therefrom may similarly beapplied to other sorts of the recording and/or reproducing data ondiscs.

3-2 Disc Layout

The disc layout for the single-layer disc, double-layer disc and then-layer disc is hereinafter explained.

FIG. 36 shows an area structure, along the radial direction of the disc,in terms of the disc layout of the single-layer disc. Meanwhile, thearrangement (radial positions) of the lead-in zone, data zone and thelead-out zone and the arrangement (radial positions) of the PB zone andthe RW zone are as explained with reference to FIG. 13 (see also FIGS.37 and 38).

As also shown in FIG. 13, the lead-in zone is made up by a BCA, apre-recorded zone PR and an OPC/DMA (a test write area and a defectmanagement area), looking from the inner rim side.

In the BCA, signals on a bar code are recorded in the radial directionin accordance with a recording system by phase change marks or with arecording system of burning off a recording layer with a high outputlaser light. This records a unique ID on each disc. This unique disc IDallows for supervising content copying to the disc 1.

As also described above, the pre-recorded data zone PR has pre-recordedtherein the disc information, such as recording and/or reproductionpower conditions, or the information used for copying protection, by thewobbled groove.

The OPC of the OPC/DMA (test write area) is used for setting theconditions for recording and/or reproduction for phase change marks,such as the recording and/or reproduction power, or the information usedfor copying protection.

The DMA (Defect Management Area) records and/or reproduces theinformation which supervises the defect information.

The data zone is an area used for recording and/or reproducing userdata.

In the data zone, an ISA (Inner Spare Area) and an OSA (Outer SpareArea) are set, ahead and in rear of a data area for recording and/orreproducing the user data, as a replacement area for replacing anon-recordable or a non-reproducible area (sectors or clusters), causedby e.g., defects, in case such non-recordable or non-reproducible areais met in e.g., use of a personal computer. It is noted that, inreal-time recording at a high transfer rate, such replacement area mayoccasionally not be set.

Although not shown, there is the DMA for recording and/or reproducingthe defect management information, in the lead-out zone, as in thelead-in zone.

The lead-out zone is also used during seek as a buffer area to allow foroverrunning.

In such one-layer disc, the addresses are sequentially recorded from theinner rim towards the outer rim, such that recording and/or reproductionby the disc driving apparatus is performed in a direction from the innerrim towards the outer rim.

FIG. 37 shows an embodiment of the double-layer disc.

In the double-layer disc, the first recording layer L0 is of the disclayout similar to that of the single-layer disc shown in FIG. 36.Meanwhile, the disc portion corresponding to the lead-out does not provethe lead-out in the meaning of the terminal portion of the recordingand/or reproduction and hence is an outer zone 0.

In the double-layer disc, the second layer L1 is sequentially formed byan outer zone 1, a data zone and a lead-out zone, looking from the outerrim towards the inner rim.

In this case, the lead-out is positioned inwardly of the position of theradius of 24 mm. In an area of the radius of 21 mm to 22.2 mm, 22.2 mmto 23.1 mm, an area of 23.1 to 24 mm, there are provided a BCA (shadedportion), a pre-recorded data zone and an OPC/DMA, respectively. In anarea of the radius of 24 to 58 mm and in an area of 58 mm to 58.5 mm,there are provided a data zone and an outer zone 1, respectively.

In this case, there is provided an area corresponding to the BCA on thesecond layer L1, however, there is recorded no unique ID.

The reason is that, when a signal on a bar code is recorded on the firstrecording layer L0 in the radial direction in accordance with arecording system of burning off the recording layer with high outputlaser light, the BCA on the second layer L1 (shaded portion) lying inregister with the BCA of the first recording layer L0 along thethickness is damaged, so that, if the BCA information, such as uniqueID, is newly recorded in the second layer L1, reliably recording canpossibly not be achieved. Stated conversely, the BCA of the firstrecording layer L0 can be improved in reliability by not performing BCArecording on the second layer L1.

On the other hand, the same information is recorded in both the firstlayer L0 and the second layer L1 for the pre-recorded data zone PR, inorder to improve the reliability of the management information andaccessibility from layer to layer.

In the data zone, ISA0 and ISA1 on the inner rim and OSA0, OSA1 on theouter rim are set in both the first layer L0 and the second layer L1 forthe data zone, as in the case of the single-layer disc, as replacementareas (sectors or clusters) as substitution for areas (sectors orclusters) that cannot be recorded nor reproduced due to e.g., defects.In realtime recording at a high transfer rate, as in video recordingand/or reproduction, such replacement areas may occasionally not be set.

In the outer zone 1, there is the defect management area for recordingand/or reproducing the defect management information.

The defect management information, recorded in the DMA on the inner andouter rim sides, records the management information for the totality oflayers.

The outer zone is also used during seek as a buffer area to allow foroverrunning.

In a double-layer disc, the addresses of the first recording layer L0are sequentially recorded from the inner rim towards the outer rim, suchthat the recording and/or reproduction is carried out in a directionfrom the inner rim towards the outer rim.

In the second recording layer L1, the addresses of the second recordinglayer L1 are sequentially recorded from the outer rim towards the innerrim, such that the recording and/or reproduction is carried out in adirection from the outer rim towards the inner rim.

In the first recording layer L0, recording and/or reproduction iscarried out from the inner rim towards the outer rim, whereas, in thesecond recording layer L1, recording and/or reproduction is carried outfrom the outer rim towards the inner rim, such that, when the recordingand/or reproduction comes to a close at the outer rim of the firstrecording layer L0, recording and/or reproduction is carried out insuccession from the outer rim of the second recording layer L1.

That is, full seek from the outer rim towards the inner rim is notrequired, such that recording and/or reproduction can be carried out insuccession from the recording layer L0 to the second recording layer L1and hence the real-time recording at a high transfer rate, such as videorecording and/or reproduction, can be performed for prolonged time.

FIG. 38 shows an embodiment of the disc layout for an n-layer disc,herein a disc with three or more layers.

In the n-layer disc, the first recording layer L0 is of the same disclayout as that for the single-layer disc or the double-layer disc,provided that a zone corresponding to the lead-out zone for thesingle-layer disc is the outer zone 0.

The second recording layer L1 is of the disc layout similar to that ofthe second recording layer L1 of the double-layer disc. It is noted thatthe lead-out zone which is the inner rim side in the second recordinglayer L1 of the double-layer disc is not the terminal end of therecording and/or reproduction with the disc with three or more layersand hence is the inner zone 1.

The n-th recording layer Ln-1 is of the disc layout similar to that ofthe second recording layer L1. For the n-th recording layer Ln-1, norecording for the BCA is made for the same reason as set forth for thesecond recording layer L1.

As for the pre-recorded data zone PR, the same information is recordedfor the first layer L0, second layer L1 . . . the n-th recording layerLn-1, for improving the reliability of the management information andfor raising the accessibility from layer to layer.

In the data zone, ISA0, ISA1 . . . ISA(n-1) on the inner rim and OSA0,OSA1 . . . OSA(n-1) on the outer rim are set in the first layer L0,second layer L1 . . . n-th layer Ln-1 for the data zone, as in the caseof the single-layer disc, as replacement areas (sectors or clusters) assubstitution for areas (sectors or clusters) that cannot be recorded norreproduced due to e.g., defects. In real-time recording at a hightransfer rate, as in video recording and/or reproduction, suchreplacement areas may occasionally not be set.

In the lead-out zone in the n-th layer, there is the DMA for recordingand/or reproducing the defect management information.

The defect management information, recorded in the DMA on the inner andouter rim sides, the management information for the totality of layersare recorded.

By recording the defect management information of the first to the n-threcording layers in one of the DMAs of the first to the n-th recordinglayers, the defect management information of the totality of layers canbe handled monistically.

Moreover, by performing defect management, with the aid of the DMAs onthe inner and outer rims of e.g., the first recording layer, and bytransferring to the defect management information of the secondrecording layer in case of failure in recording and/or reproduction bythe first layer DMA, it is possible to achieve disc management with highreliability.

If the number [n] of the n-th layer is odd-numbered, the inner rim sideof the n-th layer is an inner zone, with the outer rim side being alead-out zone.

In this case, the addresses of the n-th layer Ln-1 are sequentiallyrecorded from the inner rim towards the outer rim, such that recordingproceeds from the inner rim towards the outer rim.

If the number [n] of the n-th layer is even-numbered, the inner rim sideof the n-th layer is an lead-out zone, with the outer rim side being anouter zone.

In this case, the addresses of the n-th layer Ln-1 are sequentiallyrecorded from the outer rim towards the inner rim, such that recordingproceeds from the outer rim towards the inner rim.

With the recording and/or reproduction proceeding in this manner, fullseek from the outer rim to the inner rim is not required, as in the caseof the double layer disc, described above, such that recording and/orreproduction may be carried out sequentially from the inner rim of thefirst layer L0 to the outer rim thereof, outer rim of the second layerL1 to the inner rim thereof . . . the inner rim of the n-th layer Ln-1(for n=odd number) or the outer rim of the n-th layer Ln-1 (for n=evennumber), up to the outer rim (for n=odd number) or the inner rim of then-th layer Ln-1 (for n=even number), such that the real-time recordingat a high transfer rate, such as video recording and/or reproduction,can be performed for prolonged time.

FIG. 39 shows the spiral direction of the groove track in each recordinglayer of the disc.

In the case of a single-layer disc, the groove track is formed spirallyfrom the inner rim towards the outer rim, in a counterclockwisedirection, as shown in FIG. 39A, looking from the light beam incidentside (the side of the cover layer CVL).

In the case of a double-layer disc, the groove track is formed spirallyfrom the inner rim towards the outer rim, in a counterclockwisedirection, as shown in FIG. 39A, as in the case of the single-layerdisc.

For the second recording layer L1, the groove track is formed spirallyfrom the outer rim towards the inner rim, in a counterclockwisedirection, as shown in FIG. 39B, looking from the light beam incidentside (the side of the cover layer CVL).

In the case of an n-layer disc, in an odd-numbered recording layer(first layer L0, third layer L2, . . . ), the groove track is formedspirally from the inner rim towards the outer rim, in a counterclockwisedirection, as shown in FIG. 39A, looking from the light beam incidentside, as in the case of the single-layer disc.

In an even-numbered recording layer (second layer L1, fourth layer L3, .. . ), the groove track is formed spirally from the outer rim towardsthe inner rim, in a counterclockwise direction, as shown in FIG. 39B,looking from the light beam incident side.

By the above-described groove track structure, the recording layers ofthe totality of the phase change recording layers of the single-layerdisc, double-layer disc and the n-layer disc are recorded spirally inthe counterclockwise direction, and are recorded and/or reproduced withthe same disc rotating direction.

In the double-layer disc and in the n-layer disc, recording and/orreproduction may be achieved from the inner rim of the first layer L0 tothe outer rim thereof, outer rim of the second layer L1 to the inner rimthereof . . . the inner rim of the n-th layer Ln-1 (for n=odd number) orthe outer rim of the n-th layer Ln-1 (for n=even number), up to theouter rim (for n=odd number) or the inner rim of the n-th layer Ln-1(for n=even number), such that the real-time recording at a hightransfer rate, such as video recording and/or reproduction, can beperformed for prolonged time.

If a sole recording layer is considered, the capacity of the order of23.3 GB can be recorded and/or reproduced on or from a disc with adiameter of 12 cm, with a track pitch of 0.32 μm, a line density of 0.12μm/bit, with a data block of 64 kB as a recording and/or reproducingunit, with the formatting efficiency of approximately 82%, as discussedabove.

In this case, the data zone has 355603 clusters.

As shown in FIG. 30, the addresses are indicated by three-bit layeraddresses and 19-bit in-layer addresses (RUB addresses).

If a two-bit address is placed in one cluster, a 19-bit in-layer addressof a number odd-numbered recording layer in a data zone is 020000h and17b44ch, h denoting the hexadecimal notation, at a radial position of 24mm and a radial position of 58 mm, respectively.

The 19 bit in-layer address in a number even-numbered recording layer isa complement of the address of the number odd-numbered recording layer.

The 19 bit in-layer address in the data zone is 084bb3h and 1dffffh at aradial position of 58 mm and a radial position of 24 mm, respectively.

That is, the address is counted up from the inner rim towards the outerrim, for an odd-numbered recording layer, while being counted up fromthe outer rim towards the inner rim, for an even-numbered recordinglayer. By taking a complement of an address of the odd-numberedrecording layer for use as an address of the even-numbered recordinglayer, the in-layer address can be expressed by the number of bits ofthe in-layer addresses of one layer. On the other hand, the radialposition relationship between the odd-numbered recording layer and theeven-numbered recording layer with respect to the address can also beknown.

4. Disc Driving Apparatus

4-1 Structure

A disc driving apparatus, capable of recording and/or reproducing a disc1 as the single-layer disc and the multi-layer disc as described aboveis hereinafter explained.

FIG. 40 shows the structure of disc driving apparatus.

The disc 1 is loaded on a turntable, not shown, and is run in rotationat a constant linear velocity (CLV) by a spindle motor 52 duringrecording and/or reproduction.

The ADIP information, buried as wobbling of the groove track in a RWzone on the disc 1, is read out by an optical pickup (optical head) 51.The pre-recorded information, buried as wobbling of the groove track inthe PB zone, is also read out in similar manner.

In recording, user data is recorded as phase change marks in a track ofthe RW zone by the optical pickup 51. In replay, the phase change marksrecorded by the optical pickup 51 are read out.

In the optical pickup 51, there are formed a laser diode, as a laserlight source, a photodetector for detecting the reflected light, anobjective lens, as an output end of the laser light, and an opticalsystem, not shown, for illuminating the laser light through theobjective lens to a disc recording surface and routing the reflectedlight to the photodetector.

The laser diode outputs the so-called blue laser light with a wavelengthof 405 nm. The NA of the optical system is 0.85.

In the optical pickup 51, the objective lens is held by a biaxial unitfor movement in the tracking direction and in the focusing directions.

The entire optical pickup 51 is movable by a sled mechanism 53 along thedisc radius direction.

The laser diode in the optical pickup 51 emits laser light by a drivingsignal (driving current) from a laser driver 63.

Within the optical pickup 51, there is also provided a mechanism, aslater explained, for correcting the spherical aberration of the laserlight. The spherical aberration is corrected under control by a systemcontroller 60.

The information on the reflected light from the disc 1 is detected bythe photodetector and routed to a matrix circuit 54 as electricalsignals corresponding to the received light volume.

The matrix circuit 54 includes a current to voltage converter, a matrixoperation/amplifier circuit and so forth, for the output currents fromplural light receiving elements, operating as the photodetector, andgenerates necessary signals by matrix operation processing.

For example, high frequency signals, equivalent to replay data (replaydata signals), as well as focusing and tracking error signals for servocontrol, are generated.

Additionally, push-pull signals are generated as signals relevant togroove wobbling, that is signals for detecting the wobbling.

The replay data signals, output from the matrix circuit 54, are sent toa read/write circuit 55, while the focusing and tracking error signalsare sent to a servo circuit 61 and the push-pull signals are sent to awobble circuit 58.

The read/write circuit 55 binary encodes replay data signals andgenerates replay clocks by PLL. The read/write circuit also reproducesdata read out as phase change marks to send the so generated data to amodem 56.

The modem 56 includes a functional subsection as a decoder for replayand a functional subsection as an encoder for recording.

In replay, run length limited codes are demodulated, based on replayclocks, by way of decoding processing.

In recording, an ECC encoder/decoder 57 performs ECC encoding processingfor appending error correction codes. In replay, the ECC encoder/decoderperforms ECC decoding processing for correcting errors.

In replay, data demodulated by the modem 56 are captured by an internalmemory and subjected to error detection/correction processing anddeinterleaving to produce replay data.

The data decoded to the replay data by the ECC encoder/decoder 57 isread out under control by the system controller 60 and transferred to anAV (Audio/Visual) system 120.

The push-pull signals, output from the matrix circuit 54 as signalspertinent to groove wobbling, are processed in the wobble circuit 58.The push-pull signals, as the ADIP information, are MSK and HMWdemodulated by the wobble circuit 58 and demodulated to a datastreamforming an ADIP address which is supplied to an address decoder 59.

The address decoder 59 decodes the supplied data to obtain addressvalues which are supplied to the system controller 60.

The address decoder 59 generates clocks by PLL processing employingwobble signals supplied from the wobble circuit 58 to send the sogenerated clocks to pertinent components as encoding clocks forrecording.

The wobble circuit 58 and the address decoder 59 are configured as shownfor example in FIG. 31.

The push-pull signals, as push-pull signals output from the matrixcircuit 54 as signals pertinent to groove wobbling, and as thepre-recorded information from the PB zone, are band-pass filtered by thewobble circuit 58 and thence supplied to the read/write circuit 55. Thesignals are binary-encoded, as are the phase change marks. Thebinary-encoded signals are ECC encoded and deinterleaved by the ECCencoder/decoder 57 so that data as the pre-recorded information isextracted and supplied to the system controller 60.

The system controller 60 performs various setting and copy protectionoperations on the so read out pre-recorded information.

During recording, recorded data are supplied from the AV system 120 andsent to and buffered in a memory in the ECC encoder/decoder 57.

In this case, the ECC encoder/decoder 57 appends error correction codesor subcodes, while performing interleaving, by way of encodingprocessing for the buffered recording data.

The ECC encoded data is modulated by modem 56 in accordance with the RLL(1-7)PP system and thence supplied to the read/write circuit 55.

During recording, clocks generated from the wobble signals are used asencoding clocks used as reference clocks for encoding.

The recording data, generated by the encoding processing, is adjusted inthe read/write circuit 55 as to characteristics of the recording layers,spot shape of the laser light, fine adjustment of the optimum recordingpower as to recording linear velocity or laser driving pulse shape, andsent as laser driving pulse to the laser driver 63.

The laser driving pulse, supplied to the laser driver 63, is supplied tothe laser diode in the optical pickup 51 for laser light emission. Thisforms pits corresponding to the recording data (phase change marks) onthe disc 1.

The laser driver 63 includes a so-called APC (Auto Power Control)circuit and manages control so that the laser output will be constantirrespective of temperature, as the laser output power is monitored byan output of the laser power monitor provided in the optical pickup 51.The target value of the laser output during recording and/orreproduction is supplied from the system controller 60, so that, duringrecording and/or reproduction, control is exercised so that the laseroutput level will be at a target value.

The servo circuit 61 generates various servo driving signals, such asfocus, tracking and sled, from the focusing and tracking error signalsfrom the matrix circuit 54, to permit the servo operation to beexecuted.

That is, the servo circuit 61 generates the focusing drive signals andtracking drive signals, responsive to the focusing and tracking errorsignals, for driving the focusing and tracking coils to the biaxialmechanism in the optical pickup 51. This forms a tracking servo loop anda focusing servo loop by the optical pickup 51, matrix circuit 54, servocircuit 61 and by the biaxial mechanism.

The servo circuit 61 is responsive to a track jump command from thesystem controller 60 to turn the tracking servo loop off and to output ajump drive signal to execute the track jump.

The servo circuit 61 generates a sled drive signal, based on the slederror signal, obtained as low frequency component of the tracking errorsignals, while generating sled diving signals based on the accessingcontrol from the system controller 60, to drive the sled mechanism 53.The sled mechanism 53 includes a main shaft for holding the opticalpickup 51, a sled motor or a transmission gearing system, and drives thesled motor responsive to the sled driving signal to effect the requiredsliding movement of the optical pickup 51.

A spindle servo circuit 62 manages control to run the spindle circuit 52at CLV.

The spindle servo circuit 62 produces clocks generated by the PLLprocessing on the wobble signals as the current rotational speedinformation for the spindle motor 52 and compares the current rotationalspeed information to a preset CLV reference speed information togenerate spindle error signals.

In data reproduction, since the replay clocks generated by the PLL inthe read/write circuit 55 (clocks as reference for decoding processing)serve as the current rotational speed information of the spindle motor52, it may be compared to the preset CLV reference speed information togenerate spindle error signals.

The spindle servo circuit 62 outputs spindle driving signals, generatedresponsive to the spindle error signals, to cause the rotation of thespindle motor 52 at CLV.

The spindle servo circuit 62 is also responsive to a spindle kick/brakecontrol signal from the system controller 60 to produce the operationssuch as start, stop, acceleration or deceleration of the spindle motor52.

The above-described various operations of the servo system and therecording and/or reproducing system are controlled by the systemcontroller 60 formed by a microcomputer.

The system controller 60 executes various processing operations,responsive to a command from the AV system 120.

For example, if a write command is issued from the AV system 120, thesystem controller 60 moves the optical pickup 51 to an address to bewritten. The system controller then causes the ECC encoder/decoder 57and the modem 56 to execute the above-mentioned encoding processing ondata transferred from the AV system 120, such as video data of the MPEG2or the like system or the audio data. The recording is performed by thelaser drive pulse from the read/write circuit 55 being supplied to thelaser driver 63.

If a read command requesting the transfer of certain data recorded onthe disc 1, such as MPEG2 data, is supplied from the AV system 120, thesystem controller 60 executes seek operation control with the specifiedaddress as a target. That is, the system controller 60 issues a commandto the servo circuit 61 to cause an accessing operation of the opticalpickup 51 to be performed with the address specified by the seek commandas a target.

The system controller 60 then performs the operation control necessaryfor transferring the data of the specified data domain to the AV system120. That is, the system controller 60 causes data to be read out fromthe disc 1 to cause the read/write circuit 55, modem 56 and the ECCencoder/decoder 57 to execute the decoding/buffering to transfer therequested data.

During data recording and/or reproduction by the phase change marks, thesystem controller 60 controls the accessing and the recording and/orreproduction, using the ADIP address detected by the wobble circuit 58and by the address decoder 59.

At a preset time point, as when the disc 1 has been loaded, the systemcontroller 60 causes the unique ID recorded in the BCA of the disc 1 orthe pre-recorded information, recorded as the wobbled groove in the datazone PR, to be read out.

In this case, the system controller 60 controls the seek operation, withthe pre-recorded data zone as the target. That is, the system controller60 issues a command to the servo circuit 61 to execute an accessingoperation of the optical pickup 51 to the innermost rim of the disc.

The system controller 60 then causes the optical pickup 51 to executereplay trace to obtain push-pull signals as reflected light information,while causing the wobbling circuit 58 , read/write circuit 55 and theECC encoder/decoder 57 to execute decoding to obtain replay data as theBCA information or the pre-recorded information.

Based on the so read out BCA information or the pre-recordedinformation, the system controller 60 sets the laser power or executescopy protection processing. In reproducing the pre-recorded information,the system controller 60 controls the accessing or replay operations,using the address information contained in the BIS cluster as theread-out pre-recorded information.

In the embodiment of FIG. 40, the disc driving apparatus is connected tothe AV system 120. Alternatively, the disc driving apparatus of thepresent invention may also be connected to e.g., a personal computer.

The disc driving apparatus may also remain unconnected to otherequipment, in which case the disc driving apparatus may occasionally beprovided with an operating part or a display unit or the structure ofthe data input/output interfacing section may differ from that shown inFIG. 40. That is, it suffices that recording and/or reproduction becarried out responsive to the user operation and there be provided aterminal unit for input/output of variable data.

Of course, there are a number of other variegated possible structuresincluding a record-only device or a replay-only device.

4-2 Disc Accommodating Processing

The processing of the above-described disc driving apparatus on loadingthe disc 1 of the instant embodiment thereon is now explained withreference to FIG. 41 showing the processing centered about control bythe system controller 60.

When the disc 1 as a single-layer disc or a multi-layer disc is loadedon the disc driving apparatus, the processing by the system controller60 proceeds from step F101 to step F102, and commands the optical pickup51 to correct spherical aberration to the first layer L0 of the disc 1.

The mechanism for correcting the spherical aberration in the opticalpickup 51 is arranged and designed as shown in FIGS. 42 and 43, eachshowing an optical system in the optical pickup 51.

In FIG. 42, the laser light output from the semiconductor laser (laserdiode) 81 is collimated by a collimator lens 82 and transmitted througha beam splitter 83 to proceed via collimator lenses 87, 88 as thespherical aberration correcting mechanism so as to be illuminatedthrough an objective lens 84 on the disc 1.

The reflected light from the disc 1 is transmitted through thecollimator lenses 87,88 so as to be reflected by the beam splitter 83 tofall on a detector 86 via collimator lens (light condensing lens 85).

In such optical system, the collimator lenses 87, 88 have the functionof varying the diameter of laser light. That is, the collimator lense 87is movable along the J direction, which is the optical axis direction,to adjust the diameter of the laser light illuminated on the disc 1.

That is, at step 102 the system controller 60 exercises control to causea driving unit, not shown, of the collimator lense 87 to effect movementin the fore-and-aft direction to correct the spherical aberration to thefirst layer L0.

In an embodiment shown in FIG. 43A, a liquid crystal panel 89 isprovided in place of the collimator lenses 87, 88 of FIG. 42.

That is, in a liquid crystal panel 89, the boundary between an areaallowing for transmission of laser light and an area interrupting thelaser light is variably adjusted as indicated by a solid line, dottedline and by a chain-dotted line in FIG. 43B to vary the diameter of thelaser light.

It is sufficient in this case for the system controller 60 to issue acommand to a driving circuit driving the liquid crystal panel 89 to varythe area of transmission as described above.

After executing the correction of spherical aberration to the firstlayer L0 at step F102 of FIG. 41, the system controller 60 causes theservo circuit 61 to focus the laser light on the first layer L0.

At step F104, the BCA is accessed to read out the unique ID recorded inthe BCA.

At the next step F105, the pre-recorded zone PR is accessed to read outthe management information as the pre-recorded data.

At step F106, it is verified whether or not the management informationfor the pre-recorded zone PR has been successfully reproduced.

If the management information has been successfully reproduced, thesystem controller 60 proceeds to step F107 to sequentially test-write inan OPC (test write area) of each layer, depending on the disc type, tocalibrate the laser power.

That is, if the disc type is the single-layer disc, test write iseffected in the OPC of the first layer L0.

If the disc is the multi-layer disc, test write is effected in the OPCof each of the first layer L0 . . . n-th layer Ln-1 to set an optimumlaser power for each layer.

Meanwhile, in executing test write in each recording layer, correctionof spherical aberration and focusing control need to be executed for therecording layer for which the test write is to be prosecuted asnecessary (when the targeted recording layer is not the same as thatpreviously targeted).

After the end of the test write, the system controller 60 proceeds tostepF108 ff., to execute and control the recording and/or reproducingoperations.

Since it is the first layer L0 that is to be recorded and/or reproduced,no matter whether the disc is the single-layer disc or the multi-layerdisc, the first layer L0 is subjected to spherical aberration correctionand to focusing control for the first layer L0 to record and/orreproduce the first layer L0.

If the disc is the single-layer disc, the system controller 60 ends theprocessing when recording and/or reproducing the first layer L0 is over.

If the disc is the multi-layer disc, the system controller proceeds tostep F109 . . . F110 to effect spherical aberration correction andfocusing control sequentially for the respective layers to continue therecording and/or reproduction.

Meanwhile, with the multi-layer disc, such as a double-layer disc,recording and/or reproduction is prosecuted from the outer rim towardsthe inner rim for even-numbered recording layers, such as second layerL1. Consequently, there is no necessity of executing seek control fromthe outer rim towards the inner rim, thus enabling recording and/orreproduction to be performed continuously.

With discs with three or more layers, seek control is similarlyunnecessary in case the recording and/or reproduction proceeds from thesecond layer L1 to the third layer L2 or from the third layer L2 to thefourth layer L3, thus enabling continuous recording and/or reproduction.

Meanwhile, in actually recording and/or reproducing data, the managementinformation needs to be read out from the pre-recorded data zone PR.Although there is raised no problem when the management information hassuccessfully been read out at step F105 from the pre-recorded data zonePR of the first layer L0. If the management information has not beensuccessfully read out for some reason, the disc is disabled forrecording and/or reproduction.

It is noted that, in the multi-layer disc, the same managementinformation is recorded in the second layer ff., as described above.Thus, in the present embodiment, when the management information has notbeen read out in the first layer L0, the management information is readout from the other recording layer(s).

That is, if the replay cannot be made at step F106, the systemcontroller 60 proceeds to step F111 to verify whether or not the disc 1is a multi-layer disc. If the disc is a single-layer disc, thepre-recorded data zone PR is not readable, so that the operation isterminated as error.

If the disc is a multi-layer disc, the system controller proceeds tostep F112 to set a variable n to [2]. At step F113, correction ofspherical aberration is performed for the n-th layer, that is the secondlayer L1. At step F114, focusing control is performed for the n-thlayer, that is the second layer L1 and, at step F115, the managementinformation is read out from the pre-recorded data zone PR of the n-thlayer, that is the second layer L1.

When the replay is found to be possible at step F116, the systemcontroller 60 proceeds to step F107.

If the replay is found to be not possible at step F116, the variable nis incremented at step F117 and, at the next step F118, it is checkedwhether or not there is the n-th layer in the disc. That is, thepresence of, for example, the third layer, is checked.

If the disc is the double-layer disc, there is no third layer, and hencethe pre-recorded data zone PR is not readable. Thus, the operation isterminated as error.

If the disc is a disc with three or more layers, the n-th layer isverified to be present at step F118, so that the system controller 60reverts to step F113 to execute the correction of the sphericalaberration, focusing control and readout of the pre-recorded data zonePR for the n-th layer, that is for the third layer.

That is, it suffices that the pre-recorded data zone PR is readable forone of the totality of the recording layers.

If the pre-recorded data zone PR is found to be not readable for any ofthe recording layers, the operation is terminated as error. However, ifreadout of the pre-recorded data zone PR is possible in any recordinglayer, the system controller 60 is able to proceed to the processing ofstep F107 ff., thus improving the reliability of the disc 1.

In the above-described processing of the disc driving apparatus, boththe single-layer disc and the multi-layer disc may be coped with, whilethe spherical aberration may be optimally corrected for the recordinglayer being illuminated by the laser light. In addition, recordingand/or reproduction can be optimally prosecuted for both thesingle-layer disc and the multi-layer disc and for each recording layerof the multi-layer disc.

When the disc 1 is loaded, correction of the spherical aberration forthe first layer L0 is performed irrespective of whether the disc is thesingle-layer disc or the multi-layer disc. Since the position of thefirst layer along the disc thickness is the same for the respective disctypes, these respective disc types can be coped with satisfactorily andefficiently. That is, the pre-recorded data zone PR for the first layercan be read out without dependency on whether the loaded disc is thesingle-layer disc, double-layer disc or the three-layer disc.

The unique ID, recorded in the BCA of the first layer L0, can also beread out conveniently.

When a multi-layer disc is loaded, the management information of thepre-recorded data zone PR is read out from one of the first to the n-thlayers, the management information can be read out correctly, with ahigher probability, thus improving the operational reliability of thedisc and the disc driving apparatus.

For a multi-layer disc, test recording may be carried out for each testarea provided in each of the first to the n-th layers to set therecording and/or reproducing conditions for the respective layers torealize optimum recording and/or reproducing operations for therespective recording layers.

If the multi-layer disc is loaded, recording and/or reproduction iscarried out sequentially from the first to the n-th layers. In addition,in recording and/or reproducing an odd-numbered recording layer,recording and/or reproduction is carried out from the inner rim towardsthe outer rim of the disc. In recording and/or reproducing aneven-numbered recording layer, recording and/or reproduction is carriedout from the outer rim towards the inner rim. Consequently, therecording and/or reproduction can be carried out in succession withoutthe necessity of performing full-seek operations from the outer rimtowards the inner rim or from the inner rim towards the outer rim of thedisc, such that the real-time recording at a high transfer rate, such asvideo recording and/or reproduction, can be performed for prolongedtime.

5. Disc Producing Method

5-1 Mastering Device

The manufacturing method for the above-described optical disc 1 is nowexplained. First of all, the mastering device is explained.

The disc manufacturing process may be roughly subdivided into aso-called mastering process and a disc producing process (replicationprocess). The mastering process is up to completion of a metal masterdisc (stamper) used for the disc producing process, and the discproducing process is the process of producing a large number of opticaldisc, as replicated products.

Specifically, during the mastering process, a photoresist is coated on apolished glass substrate, and the resulting photosensitive film isexposed to laser light to form a groove.

This processing is carried out by a mastering device.

In the present embodiment, groove mastering is performed in an area ofthe glass substrate in register with the PB zone of the innermost discrim, by wobbling based on the pre-recorded information, while groovemastering is performed in an area of the glass substrate in registerwith the RW zone, by wobbling based on the ADIP address. A plural numberof stampers, namely a stamper for the first layer L0, a stamper for thesecond layer L1 . . . a stamper for the n-th layer Ln-1, are prepared.The mastering device is shown in FIG. 44.

The mastering device includes a pre-recorded information generator 71,an address generator 72, a selector 73, a wobble data encoder 74, awobble address encoder 75 and a controller 70.

The mastering device also includes a laser light source 82, a opticalmodulator 83, a head unit 84, a transfer mechanism 77, a spindle motor76, a head transfer controller 78 and a spindle servo circuit 79.

The pre-recorded information for recording is produced in a preparationstep termed mastering.

The pre-recorded information generator 71 outputs the pre-recordedinformation produced in the pre-mastering step.

This pre-recorded information is encoded by the wobble data encoder 74to produce stream data of a wobble waveform modulated with thepre-recorded information. The so produced stream data is sent to theselector 73.

The address generator 72 sequentially outputs values of the absoluteaddresses.

The groove is subjected to MSK modulation and HMW modulation in thewobble address encoder 75, based on the absolute address values of theoutput by the address generator 72. This wobble address encodergenerates encoded signals, as the address information for MSK modulatingthe groove and as the address information for HMW modulating the groove,to send the resulting encoded signals to the selector 73.

For MSK modulation, two frequencies, namely cos(ωt) and cos(1.5ωt), aregenerated, on the basis of the reference clocks. From the addressinformation, a datastream, containing the data for modulation,synchronized with the reference clocks, at a preset timing position, isgenerated. The datastream is MSK modulated with for example twofrequencies of cos(ωt) and cos(1.5ωt) to generate MSK modulated signals.In the groove portion where the information is not subjected to the MSKmodulation, a signal with the waveform of cos(ωt) (monotone wobble) isgenerated.

As for the HMW modulation, a second harmonics signal (±sin(2ωt))synchronized with cos(ωt) generated in the above-described MSKmodulation is generated based on the reference clocks. This secondharmonics signal is output at a timing of recording the addressinformation with HMW modulation (a timing of the monotone wobble notsubjected to MSK modulation). It is noted that the second harmonicssignal is output as switching is made between +sin(2ωt) and −sin(2ωt)depending on the digital code of the input address information.

The second harmonics signal as the HMW modulated output is summed to theMSK modulated signal. The resulting sum signal is supplied as a wobbleaddress signal stream to the selector 73.

The head unit 84 illuminates a light beam to a glass substrate 101,coated with a photoresist, for light exposure of the groove track.

The spindle motor 76 causes rotation of the glass substrate 101 at CLV.The spindle servo circuit 79 manages rotational servo control.

The transfer mechanism 77 transfers the head unit 84 at a constantvelocity from the inner rim towards the outer rim or from the outer rimtowards the inner rim, so that the light beam is spirally illuminatedfrom the head unit 84.

The head transfer controller 78 executes the operation of the transfermechanism 77.

A laser light source 82 is formed e.g., by He—Cd laser. The opticalmodulator 83 for modulating the outgoing light from the laser lightsource 82 based on the recording data is an acousto-optical deflector(AOD) adapted for deflecting the outgoing light from the laser lightsource 82 based on the wobble generating signal.

The selector 73 selects a wobble waveform signal as the pre-recordedinformation and the wobble waveform stream as the address information tosend the signal and datastream thus selected to a wobble deflectiondriver 81.

The wobble deflection driver 81 drives the light deflector of theoptical modulator 83 in dependence upon the pre-recorded informationsupplied thereto or upon the wobble waveform stream as the addressinformation.

The laser light, output from the laser light source 82, is deflected bythe optical modulator 83, responsive to the pre-recorded information andthe wobble waveform stream, as the address information, so as to beilluminated by the head unit 84 on the glass substrate 101.

As described above, the glass substrate 101 is run in rotation at CLV bythe spindle motor 76, while the head unit 84 is transferred at a presetvelocity by the transfer mechanism 77, so that a wobbled groove patternas indicated in FIGS. 21A, 22A, 23A, 24A, 25A, 27A or 28A is sensitizedon the photoresist surface of the glass substrate 101.

The controller 70 prosecutes and controls the mastering operation, whilecontrolling the pre-recorded information generator 71, address generator72 and the selector 73 as the controller 70 monitors the transferposition of the transfer mechanism 77.

In starting the stamper mastering for forming odd-numbered recordinglayers, such as the first layer L0 or the third layer L2, the controller70 sets the innermost portion, in register with the pre-recorded datazone PR, as the initial position of the transfer mechanism 77. Thecontroller 70 then initiates the rotation of the glass substrate 101 atCLV and sliding transfer for forming the groove with a track pitch of0.35 μm.

In this state, the controller 70 causes the pre-recorded information tobe output from the pre-recorded information generator 71 and sent to thewobble deflection driver 81 via selector 73. The controller 70 alsoinitiates the laser outputting from the laser light source 82. Theoptical modulator 83 modulates the laser light, depending on the drivingsignal from the wobble deflection driver 81, that is FM code modulatingsignal of the pre-recorded information, to execute groove mastering onthe glass substrate 101.

The groove wobbled in accordance with the pre-recorded information ismastered in this manner in an area of the first layer L0 and the thirdlayer L2 in register with the pre-recorded data zone PR.

Subsequently, on detecting that the transfer mechanism 77 has proceededto a location in register with the RW zone, the controller 70 commandsthe selector 73 to be switched to the side of the address generator 72,while also commanding the address generator 72 to sequentially generateaddress values. For example, if the mastering is for the stamper usedfor generating the first layer L0, the address values [020000h] to[17644ch] are sequentially generated.

The controller 70 also lowers the slide transfer speed of the transfermechanism 77 for forming the groove with the track pitch of 0.32 μm.

In this manner, the wobble waveform stream, derived from the addressinformation, is sent from the address generator 72 to the wobbledeflection driver 81. The laser light from the laser light source 82 ismodulated by the modulator 83 based on the driving signal from thewobble deflection driver 81, that is on the MSK/HMW modulation signal ofthe address information, such that groove mastering on the glasssubstrate 101 is achieved by the modulated laser light.

In this manner, the groove wobbled in accordance with the addressinformation is mastered in an area in register with the RW zone.

On detecting that the transfer by the transfer mechanism 77 has reachedthe terminal end of the lead-out zone or the outer zone, the controller70 terminates the mastering operation.

In starting the mastering of the stamper used for forming theeven-numbered recording layer, such as the second layer L1 or the fourthlayer L3, the controller 70 sets the outermost rim, equivalent to theouter zone, as an initial position for the transfer mechanism 77, andinitiates the rotation of the glass substrate 101 at CLV and slidingtransfer thereof for forming a groove to a track pitch of 0.32 μm.

In this case, the controller 70 commands the selector 73 to be switchedto the side of the address generator 72, while commanding the addressgenerator 72 to sequentially generate address values.

If the mastering is for the stamper used for generating the second layerL1, the address values of [084bb3h] to [1dffffh] are sequentiallygenerated.

This supplies the wobble waveform stream, derived form the addressinformation, from the address generator 72 to the wobble deflectiondriver 81. The laser light from the laser light source 82 is modulatedin the modulator 83, in accordance with the driving signals from thewobble deflection driver 81, that is the MSK/HMW modulation signal ofthe address information. The resulting modulated laser light is thenused to achieve the groove mastering on the glass substrate 101.

In this manner, the groove wobbled in accordance with the addressinformation is mastered in an area of the glass substrate in registerwith the RW zone.

When the controller 70 has detected that the transfer of the transfermechanism 77 has reached a position in register with the pre-recordeddata zone PR, the slide transfer for forming the groove of a track pitchof 0.35 μm is initiated.

Under this condition, the pre-recorded information is output from thepre-recorded information generator 71 and supplied via selector 73 tothe wobble deflection driver 81. The controller 70 also initiates thelaser outputting from the laser light source 82. The optical modulator83 modulates the laser light based on the driving signal from the wobbledeflection driver 81, that is on the FM code modulation signal of thepre-recorded information, to execute groove mastering on the glasssubstrate 101.

In this manner, the groove wobbled in accordance with the pre-recordedinformation is mastered in the area in register with the pre-recordeddata zone PR of each of the second layer L1, fourth layer L3 and soforth.

On detecting that the terminal end of the pre-recorded data zone PR isreached, the mastering operation is terminated.

By the above sequence of operations, a light exposed portion is formedon the glass substrate 101 which is in register with the wobbled grooveas the PB zone and the RW zone.

The stamper is then completed on developing, electroforming etc.

Specifically, a stamper for the first layer, a stamper for the secondlayer . . . and a stamper for the n-th layer are produced.

5-2 Producing Sequence

FIG. 45 shows the sequence of operations for producing the disc afterthe manufacture of the stamper for each recording layer as describedabove.

<procedure P1>

A substrate RL of for example polycarbonate is formed on injection,using a stamper for the first layer, and a groove pattern istranscribed, after which a recording film as the first layer L0 isformed on sputtering.

<procedure P2>

By injection employing a stamper for the second layer, an intermediatelayer ML, having a groove pattern transcribed thereto, is formed, and arecording film as the second layer L1 is formed by a sputtering device.

<procedure P3>

By injection employing a stamper for the n-th layer, an intermediatelayer ML, having a groove pattern transcribed thereto, is formed, and arecording film as the n-th layer Ln-1 is formed by a sputtering device.

<procedure P4>

In producing a single-layer disc, a cover layer CVL is formed to athickness of approximately 100 μm on the layer formed at procedure P1.

<procedure P5>

In producing a single-layer disc, a cover layer CVL is formed to athickness of approximately 75 μm on the layer formed by procedures P1and P2.

<procedure P6>

In producing an n-th-layer disc, where n is here three or more, a coverlayer CVL is formed to a thickness of 100−(n-1)×25 μm on the layerformed by procedures P1, P2 and P3.

In producing a single-layer disc, a BCA is recorded on the disc formedat the procedure P4 above to complete the disc 1.

In producing a double-layer disc, a BCA is recorded on the disc formedat the procedure P5 above to complete the disc 1.

In producing a three-layer disc, a BCA is recorded on the disc formed atthe procedure P6 above to complete the disc 1.

As may be seen from the above manufacturing process, the single-layerdisc is produced by P1→P4→BCA recording, while the double layer disc isproduced by P1→P2→P5→BCA recording and the n-th layer is produced byP1→P2→P3→P6→BCA recording.

The process up to step P1 is common to all discs. Moreover, theprocedures P1 and P2 are common to the double-layer disc and thethree-layer disc, for example, thus simplifying the process.

5-3 BCA Recording Device

FIG. 46 shows a recording device for recording the BCA.

The BCA recording device includes a controller 90, a BCA data generator91, a BCA encoder 92, a laser driver 93, an optical head 94, a transfermechanism 95, a spindle motor 96, a head transfer controller 97 and aspindle servo circuit 98.

The disc, prepared as described above, is run in rotation at for exampleCAV by the spindle motor 96, under rotational control by the spindleservo circuit 98.

The transfer mechanism 95 transfers the optical head 94 within the rangeof BCA of the disc.

The BCA data generator 91 generates the information as a unique IDproper to each disc. The data as this unique ID is encoded by the BCAencoder.

The laser driver 93 on/off modulation controls the laser output in theoptical head 94 based on the encoded data.

The controller 90 controls the execution of the above-describedoperations.

By this BCA recording device, the high power laser light is outputmodulated with the unique ID data from the optical head 94. Moreover,since the disc 96 is rotated at CAV, the BCA data is recorded asconcentric bar-code information as the BCA of the disc 1.

While the present invention has been with reference to a disc and anassociated disc driving apparatus, the present invention is not limitedto these particular embodiments and may be variably constructed withinthe scope of the invention.

While the invention has been described in accordance with certainpreferred embodiments thereof illustrated in the accompanying drawingsand described in the above description in detail, it should beunderstood by those ordinarily skilled in the art that the invention isnot limited to the embodiments, but various modifications, alternativeconstructions or equivalents can be implemented without departing fromthe scope and spirit of the present invention as set forth and definedby the appended claims.

INDUSTRIAL APPLICABILITY

As may be understood from the foregoing explanation, the followingfavorable effect may be obtained in accordance with the presentinvention.

With the disc-shaped recording medium, or the disc manufacturing method,according to the present invention, the recording layer, as a firstrecording layer, a single layer disc or a multi-layer disc, havingplural recording layers, the recording layer as a first recording layeris formed at such a position in a direction of thickness of the discthat the distance from the surface of a cover layer on which the lightenters for recording and/or reproduction to the first recording layer isthe same as the distance in case of the single layer disc. Thus, in thesingle layer disc, a double layer disc, a three layer disc, or a discwith four or more recording layers, the recording layer as the firstlayer, such as a recording layer of the phase change recording film, maybe formed in similar manner on a polycarbonate substrate, so that themanufacturing process may be partially common, while similar recordingand/or reproducing characteristics may be obtained for both the singlelayer disc and the multi-layer disc.

Moreover, with the multi-layer disc, the second recording layer isformed at such position which is closer to the cover layer surface thansynchronous detection first layer, so that the second recording layer isformed at smaller distance from the surface of the cover layer. Thesecond recording layer is formed of a plurality of recording layers.That is, the thickness of the cover layer becomes thinner as seen fromthe respective layers. This increases the tilt angle allowance betweenthe disc and the light beam. That is, the tilt margin for the secondrecording layer may be relaxed as compared to that of the recording filmof the first layer, thus improving the recording and/or reproducingcharacteristics and disc productivity, while lowering the productioncost.

In the first to the n-th recording layers, the odd-numbered recordinglayers and the even-numbered recording layers are recorded and/orreproduced from the inner rim towards the outer rim and from the outerrim towards the inner rim of the disc, respectively. Thus, at a timepoint when for example the first recording layer has been recorded orreproduced at the outer rim, the second recording layer may be recordedor reproduced as from the outer rim. That is, full seek from the outerrim towards the inner rim or from the inner rim towards the outer rim isnot required, in prosecuting the recording and/or reproducing operationsfrom a given recording layer to the next, such that the real-timerecording at a high transfer rate, such as video recording and/orreproduction, can be performed for prolonged time.

The addresses of odd-numbered recording layers of the first to the n-threcording layers are sequentially recorded from the inner rim towardsthe outer rim of the disc, while the addresses of even-numberedrecording layers are obtained on complementing the addresses of theodd-numbered recording layers at the positions radially corresponding tosynchronous detection addresses of the even-numbered recording layers,and are recorded from the outer rim towards the inner rim of the disc.That is, the addresses are counted up from the inner rim towards theouter rim in the odd-numbered recording layers, such as the first andthird recording layers, while being counted from the outer rim towardsthe inner rim for the even-numbered recording layers, such as the secondand fourth recording layers. By complementing the addresses of theodd-numbered recording layers as the addresses of the even-numberedrecording layers, the addresses in one layer can be expressed by thenumber of bits of the addresses in the one layer. This addressing systemis convenient as the addressing system when it is desired to increasethe recording capacity by employing plural recording layers. Theposition relationships along the radial direction with respect to theaddresses of the odd- and even-numbered recording layers can also beknown.

Moreover, a unique ID proper to the disc-shaped recording medium isrecorded only in the first recording layer by a recording system ofburning off the recording layer, as stated as BCA. When the bar codesignals are recorded along the radial direction by the recording systemof burning off the first recording layer, there is a risk of damagingother recording layers lying at the same position along the direction ofdisc thickness, such that the unique ID cannot be reliably recorded inthese other layers. The unique ID may be improved in recording and/orreproducing reliability by recording only in the first recording layer.

The management information for recording and/or reproduction is recordedin each of the first to the n-th recording layers, as the replay-onlyinformation, by wobbling a groove which is formed spirally on the disc.The management information can be recorded to high reliability, and maybe read in each layer, by recording the management information, such asthe disk information, including the conditions for recording and/orreproducing power, or the copy protection information, as thepre-recorded information by track wobbling, thus improving theaccessibility.

The recording test area is provided in each of the first to the n-threcording layers to enable the recording test to be conducted in eachlayer in a manner suited to the layer in question to find out optimumrecording and/or reproducing conditions.

The defect management information for the first to the n-th recordinglayers is recorded in each of the first to the n-th recording layers, sothat the defect management information for the totality of the recordinglayers can be handled monistically.

If the defect management information cannot be recorded in for examplethe first recording layer, the recording position of the defectmanagement information can be switched to the second layer, third layeretc., to assure defect management to high reliability.

The first to the n-th recording layers are provided with replacementareas to provide the replacement areas of the same recording capacity inthese recording layers to exploit the defect management efficiency inthe respective recording layers effectively with high accessibility.

The disc driving apparatus of the present invention is able to cope withboth a single layer disc and a multi-layer disc and in particular isable to correct spherical aberration in dependence upon the recordinglayer to be illuminated with the laser light, thus allowing to recordand/or reproduce the single layer disc and the multi-layer disc and therespective recording layers of the multi-layer disc with highadaptability.

When the disc-shaped recording medium is loaded, the sphericalaberration correction is carried out for the first layer without regardto whether the disc is a single layer disc or a multi-layer disc. Sincethe position of the first layer along the direction of disc thickness isthe same without regard to whether the disc is a single layer disc or amulti-layer disc, the respective disc types can be coped withsatisfactorily and efficiently.

When the disc-shaped recording medium is loaded, the unique ID proper tothe disc-shaped recording medium, recorded by burning off the firstrecording layer, may be read out to enable the unique ID to be read outin dependency upon the disc type.

If the disc loaded is the multi-layer disc, the management informationfor recording and/or reproduction, recorded as the replay-onlyinformation by wobbling the spirally formed groove, may be read out fromany of the first to the n-th layer. That is, if the managementinformation cannot be read in the first layer, the recording and/orreproducing operation can be prosecuted by reading out the managementinformation from another recording layer, thus improving the operationalreliability.

Moreover, in a multi-layer disc, test recording may be carried out inthe test area provided in each of the first to n-th layer to set therecording and/or reproducing conditions to realize optimum recordingand/or reproducing conditions.

Additionally, in a multi-layer disc, the defect management informationfor the first to the n-th layer may be recorded in any of the defectmanagement areas provided in the respective recording layers, wherebythe defect management information of the totality of the recordinglayers can be handled monistically.

On the other hand, if the defect management information cannot berecorded and/or reproduced in the first recording layer, the recordingposition for the defect management information can be switched to thesecond or third layer, thus achieving defect management to highreliability.

If the disc loaded is the multi-layer disc, recording and/orreproduction may be prosecuted sequentially from the first layer to then-th layer. During recording and/or reproduction for the odd-numberedrecording layer, recording and/or reproduction may be prosecuted fromthe inner rim towards the outer rim of the disc, whereas, duringrecording and/or reproduction for the even-numbered recording layer,recording and/or reproduction may be prosecuted from the outer rimtowards the inner rim of the disc, so that recording and/or reproductioncan be continuously prosecuted without full seek from the outer rimtowards the inner rim of the disc. As a result, the real-time recordingat a high transfer rate, such as video recording and/or reproduction,can be performed for prolonged time.

From the foregoing, the present invention gives such a favorable effectthat the present invention is suitable for a large-capacity disc-shapedrecording medium and that the recording and/or reproducing performanceof the disc driving apparatus is improved.

1. In a disc-shaped recording medium which may be a single-layer disc,having a single recording layer, or a multi-layer disc having aplurality of recording layers, a disc-shaped recording medium which issaid multi-layer recording medium wherein the recording layer as a firstrecording layer is formed at such a position in a direction of thicknessof the disc that the distance from the surface of a cover layer on whichthe light enters for recording and/or reproduction to the firstrecording layer is the same as the distance in case of said single layerdisc; and wherein the second recording layer is formed at such positionwhich is closer to said cover layer surface than said first layer. 2.The disc-shaped multi-layer recording medium according to claim 1,wherein the second recording layer is formed of a plurality of recordinglayers.
 3. The disc-shaped multi-layer recording medium according toclaim 1 wherein, of the first to the n-th recording layers, odd-numberedrecording layers are recorded and/or reproduced from the inner rimtowards the outer rim of the disc, and even-numbered recording layersare recorded and/or reproduced from the outer rim towards the inner rimof the disc.
 4. The disc-shaped multi-layer recording medium accordingto claim 1 wherein the addresses of odd-numbered recording layers of thefirst to the n-th recording layers are sequentially recorded from theinner rim towards the outer rim of the disc, and wherein the addressesof even-numbered recording layers are obtained on complementing theaddresses of the odd-numbered recording layers at the positions radiallycorresponding to said addresses of the even-numbered recording layers,are recorded from the outer rim towards the inner rim of the disc. 5.The disc-shaped multi-layer recording medium according to claim 1wherein a unique ID proper to the disc-shaped recording medium isrecorded only in the first recording layer by a recording system ofburning off the recording layer.
 6. The disc-shaped multi-layerrecording medium according to claim 1 wherein the management informationfor recording and/or reproduction is recorded as replay-only informationin each of the first to the n-th recording layers by wobbling a grooveformed for spirally extending in said disc.
 7. The disc-shapedmulti-layer recording medium according to claim 1 wherein a test areafor conducting a recording test is provided in each of said first ton-th recording layers.
 8. The disc-shaped multi-layer recording mediumaccording to claim 1 wherein an area for recording the defect managementinformation for each of said first to n-th recording layers is providedin each of said first to n-th recording layers.
 9. The disc-shapedmulti-layer recording medium according to claim 1 wherein a replacementarea is provided in each of said first to n-th recording layers.
 10. Adisc driving apparatus for recording and/or reproducing a disc-shapedrecording medium which may be a single-layer disc, having a singlerecording layer, or a multi-layer disc having a plurality of recordinglayers, wherein the recording layer as a first recording layer of saidmulti-layer disc is formed at such a position in a direction ofthickness of the disc that the distance from the surface of a coverlayer on which the light enters for recording and/or reproduction to thefirst recording layer is the same as the distance in case of said singlelayer disc; and wherein the second recording layer is formed at suchposition which is closer to said cover layer surface than said firstlayer; said apparatus comprising: head means for illuminating the laserlight for recording and/or reproducing data for a track of each of saidrecording layers; correction means for correcting the sphericalaberration of said laser light; and correction controlling means forcontrolling said correction means, in dependence upon the recordinglayer to be illuminated by said laser light to correct sphericalaberration in dependence upon the recording layer.
 11. The disc drivingapparatus according to claim 10, wherein the second recording layer isformed of a plurality of recording layers.
 12. The disc drivingapparatus according to claim 10 wherein said correction controllingmeans causes said correction means to execute spherical aberrationcorrection for said first layer, on loading of said disc-shapedrecording medium, without regard to the disc type.
 13. The disc drivingapparatus according to claim 10 wherein a unique ID proper to thedisc-shaped recording medium, recorded in said first layer by arecording system of burning off the layer, is read out on loading thedisc-shaped recording medium.
 14. The disc driving apparatus accordingto claim 10 wherein, when the multi-layer disc having n recording layersis loaded, the management information for recording and/or reproduction,recorded as the replay-only information by wobbling a spirally formedgroove, is read out from one or more of the first to the n-th recordinglayers of the disc.
 15. The disc driving apparatus according to claim 10wherein, when the multi-layer disc having n recording layers is loaded,test recording is carried out in a test area provided in each of saidfirst to n-th recording layers.
 16. The disc driving apparatus accordingto claim 10 wherein, when the multi-layer disc having n recording layersis loaded, the defect management information for the first to the n-threcording layers is recorded in a defect management area provided ineach of said first to n-th recording layers.
 17. The disc drivingapparatus according to claim 10 wherein, when the multi-layer dischaving n recording layers is loaded, recording and/or reproduction issequentially prosecuted from the first to the n-th recording layers. 18.The disc driving apparatus according to claim 10 wherein, in recordingand/or reproducing odd-numbered recording layers of said disc-shapedrecording medium, recording and/or reproduction is executed from theinner rim towards the outer rim of the disc, and wherein, in recordingand/or reproducing even-numbered recording layers of said disc-shapedrecording medium, recording and/or reproduction is executed from theouter rim towards the inner rim of the disc.
 19. A method for producing,of a single-layer disc, having a single recording layer, and amulti-layer disc, having a plurality of recording layers, a disc-shapedrecording medium which is said multi-layer recording medium, said methodcomprising: forming the recording layer as a first recording layer atsuch a position in a direction of thickness of the disc that thedistance from the surface of a cover layer on which the light enters forrecording and/or reproduction to the first recording layer is the sameas the distance in case of said single layer disc; and forming thesecond layer at such position which is closer to said cover layersurface than said first layer.
 20. The method for producing adisc-shaped multi-layer recording medium according to claim 19 wherein,the second recording layer is formed of a plurality of recording layers.21. The method for producing a disc-shaped multi-layer recording mediumaccording to claim 19 wherein, of the first to the n-th recordinglayers, odd-numbered recording layers are recorded and/or reproducedfrom the inner rim towards the outer rim of the disc, and even-numberedrecording layers are recorded and/or reproduced from the outer rimtowards the inner rim of the disc.
 22. The method for producing adisc-shaped multi-layer recording medium according to claim 19 whereinthe addresses of odd-numbered recording layers of the first to the n-threcording layers are sequentially recorded from the inner rim towardsthe outer rim of the disc, and wherein the addresses of even-numberedrecording layers are obtained on complementing the addresses of theodd-numbered recording layers at the positions radially corresponding tosaid addresses of the even-numbered recording layers, and are recordedfrom the outer rim towards the inner rim of the disc.
 23. The method forproducing a disc-shaped multi-layer recording medium according to claim19 wherein a unique ID proper to the disc-shaped recording medium isrecorded only in the first recording layer by a recording system ofburning off the recording layer.
 24. The method for producing adisc-shaped multi-layer recording medium according to claim 19 whereinthe management information for recording and/or reproduction is recordedas replay-only information in each of the first to the n-th recordinglayers by wobbling a groove formed for spirally extending in said disc.25. The method for producing a disc-shaped multi-layer recording mediumaccording to claim 19 wherein a test area for conducting a recordingtest is provided in each of said first to n-th recording layers.
 26. Themethod for producing a disc-shaped multi-layer recording mediumaccording to claim 19 wherein an area for recording the defectmanagement information for each of said first to n-th recording layersis provided in each of said first to n-th recording layers.
 27. Themethod for producing a disc-shaped multi-layer recording mediumaccording to claim 19 wherein a replacement area is provided in each ofsaid first to n-th recording layers.